The numbers are about right for Fighter Command and Luftwaffe losses; precise figures can be a little tricky, the BBC have a [day-by-day breakdown] (http://www.bbc.co.uk/news/uk-11029903) using data from After the Battle: Then and Now, the source data also available to download. Their totals come out to 2662 for the Luftwaffe, 537 for Fighter Command. Note, though, that the figures are for airmen, not just pilots, which is one reason the German figures are much higher: many of their losses were medium bombers with four or five crew (also Bf 110 heavy fighters and Ju 87 dive bombers with two crew). The vast majority of Fighter Command flew the Spitfire and Hurricane, single-seat fighters (though there were a few squadrons of Blenheim fighters and Defiants with both pilots and gunners).

The other main reason for the difference, as you surmise, is that RAF pilots who crash landed or bailed out over Britain could quickly be back in action (on the same day sometimes) whereas surviving Luftwaffe aircrew were taken prisoner (with almost no chance of escape; one pilot, Franz von Werra, eventually returned to Germany, after being taken to Canada and escaping to the then-neutral US, but I believe he was the only one). You can see from the day-by-day breakdown that Fighter Command aircrew losses as a percentage of aircraft losses are higher in July and early August; this was the Kanalkampf, when the Luftwaffe focused on attacking shipping in the English Channel and pilots who ditched in the Channel had slim hopes of being rescued. Once the Luftwaffe focus on RAF bases and then London from mid-August, with most of the fighting over land, relative RAF aircrew losses tend to be much lower.

Note also that the above figures only refer to Fighter Command of the RAF, as generally the Battle of Britain only refers to the daylight battles between Fighter Command and the Luftwaffe; RAF Bomber Command were also active in the same period, bombing targets from airfields and invasion barges in occupied Europe to strategic targets in Germany itself, and though their aircraft losses were only about one third of Fighter Command (376 vs ~1000), their aircrew losses were almost twice as high (around 1000 killed or captured), again due to the multiple crew per bomber, and the fact that crew who bailed out were liable to be captured).

It can also be added that although there was quite an extensive system in place for rescue of downed pilots over the channel it still required pilots being able to bring a damaged plane back to the "right" side of the channel. With most of the fight on the British side of it it naturally means that the German pilots were hard-pressed in managing to bring a plane back to those rescue efforts. Generally only the Bf 109 fighter planes (the "Messerschmitts") were fast enough to make such an attempt; they were at least fast enough to be able to keep even a "souped up" Spitfire at a distance for a few minutes until reaching the French side.

The unfortunate airmen who needed to parachute often drowned as the risk of getting tangled in the parachute was high, and even if you managed the parachuting-part there was a great risk of dying to hypothermia. For British pilots who mostly had closer to home (bomber crews notwithstanding) could often parachute over land instead, or emergency-land out of reach of enemy fighters (even just a couple of minutes of flight could get you far enough away to be "dropped" by a pursuer and not be interesting to new ones, especially with the fuel limitations imposed on the Germans and the poor range of the 109). It certainly didn't help that the British had no truly organized sea rescue effort, so although there were many boats and many willing boatsmen it was difficult to find the downed airmen without coordination with observer/rescue planes or coastal spotters.

The Luftwaffe had its own sea rescue service - the "Seenotdienst" - which was an originally civilian service brought into the military. This service rescued downed pilots - both German and enemy ones - both with purpose-built (or purpose-modified to be more exact) rescue float-planes, and with a steadily growing fleet of rescue motor boats often operated by civilian organisations.

Due to the losses suffered during the Battle of Britain a rescue-buoy - "Rettungsbojen" - system was also implemented at the initiative of Ernst Udet, the "father" of the dive bomber and at that time the director-general of equipment for the Luftwaffe. These buoys were yellow, easily seen floating rescue shelters with beds, food, and water which boats of the Seenotdienst regularly checked (there was a signal flag too to signal a buoy was in use, and these could be seen from land at least in clear weather), and they were placed with regular intervals along the channel coast. The shelters were available to airmen of both sides, and being relatively easy to find the intention was for pilots to ditch near them and then swim/paddle to them.

The Seenotdienst and Luftwaffe also did their research on physiological effects of being in cold water for long periods of time and developed more rescue equipment and methods of rescue, like special heating blankets, flourescent dye to mark one's location in the water, inflatable dingies, procedures for how to treat hypothermia, better routines for how to safely ditch a plane in water, etc. Cruelly enough the effects and treatment of hypothermia were - when the urgent need for it was discovered by the alarming rate of post-rescue deaths - artifically studied by forced (and often brutal) methods on concentration camp prisoners, as far as I know being the first methodical medicinal studies of the effect.

Despite all these efforts however a lot of pilots were lost to the cold waters, and it certainly didn't help that both sides attacked each others' rescue boats and planes, in particular after Churchill ordered the rescue planes to be shot down as the military suspected them of espionage/military observation. Neither the buoys nor dingies or hypothermia-research was in place until after the end of the Battle of Britain (i.e. until the end of October 1940) however, so most of the lessons learned from those three bloody months weren't in effect until the sustained but lower-intensity battle of the channel that followed. It can be added that the British later (in 1941) copied the German Seenotdienst as they had a constant need for it with returning bombers often having to ditch in the channel. For exact methods used by the British and American commands I refer to someone else however. I have mostly looked at the Germans.

The services on both sides rescued many thousands of airmen between 1940 and 1945. The British and Americans alone rescued ~10 000, and although I for years have been unable to find any total number for German rescues it is not beyond reason that 15 000 - 20 000 (half of them airmen) were rescued in total along the British Channel, French west-coast, and up along Belgium, Netherlands, Denmark, and Norway.