To points 1) and 2), they did! American and British bombers launched a series of raids against the Normandy defenses. However, the raids failed to damage and destroy most of the beaches' actual defenses. The bombs fell onto German rear areas and secondary defenses. And unfortunately, the heavy naval artillery likewise shot over the German's defenses. However, destroyers used their 5" guns to great effect in supporting the assault. Many of those destroyers risked running their ships aground, or being hit by German artillery on the beaches. But their support was critical, and without it the attack may have never succeeded.

As to why Normandy, and not some other place, Normandy was the best spot. The amphibious craft of the time really required a soft and sandy beach, not a rocky, cliffy beach. That immediately limited the places where you could go, especially with England as the starting place. Really, using England as a base, the most direct route to France was across the Channel. The British and Americans could close the channel with their battle fleets, which would prevent German interference, and they could cross in hours. That meant that the Germans would only have a few hours warning, if any, as to what was happening. If you were to ship all of those troops out of England, and around to Bordeaux or the Azure Coast, the Germans would have had ample time to simply reinforce those beaches.

Too, you have to consider the geography of France. Normandy is close to Paris (the capital), its close to Calais and Cherbourg, good channel ports for importing supplies, and Calais is just a skip away from Antwerp, the largest port in Europe. All that makes supplying an army on the Franco-German border easy. If you started from Bordeaux or Marseilles (in the east or south, respectively), the army would start on the other side of France, and all those supplies would have had to been ferried from southern and eastern France towards Paris. It would have been a logistical nightmare, for very little gain.

The real crux of the issue is, while casualties may have been harsh when piercing the German's Atlantic Wall, every beach succeeded in doing so, on the first day. No unit was pushed back into the sea, they didnt sleep on the beaches, and the attack was really quite successful. It was also the perfect embodiment of the American way of war during World War Two. Many in the army, especially in the planning sections, favored decisive attacks rather than maneuver warfare. The argument was, it was better to take some casualties now, and win, than to take fewer casualties for longer, while you got in position to win. In that context, I really see D-Day as one of those "well take the lumps now to get a tangible victory now" moments.

Sources:

Russell Weigley, The American Way of War

Russell Weigley, Eisenhower's Lieutenants

Williamson Murray and Alan Millett, A War to be Won

One other point that should be made is that at Omaha Beach specifically, the troops manning the emplacements were elements of the 352nd Infantry Division. Unlike other units on the Atlantic Wall, which were "static" units, basically garrison troops, the 352nd, while it was a new unit formed in 1943, was a formation composed of Eastern Front veterans (including a sizable amount of non-German troops, like Belorussians) and was probably one of the better equipped formations in the Western Front. It is also said that some of these troops were on a defensive training mission at the time of the attack, although the main source for this is Werner Pluskat, an artillery officer in the 352nd.

Source:

Conrelius Ryan, The Longest Day

Well, what happened at Omaha Beach wasn't really planned. Many things didn't go right. First off, the bombing runs missed. Bombs meant for the fortifications landed miles inland on farmland. The bombardment by the navy, if I remember correctly, was only partially on target and didn't really do much. In Cornelius Ryan's The Longest Day there is an account by a German soldier who stated that the barrage, though fierce, failed to effectively destroy defenses and that the emplacements manned by he and his comrades remained mostly intact. When the troops were launched from the ships, there was a good deal of confusion and more importantly, the infantry were dumped onto a sandbar about 100 yards from the beach if memory serves me right. As a result, the infantry ended up having to slowly but surely make their way to the beach through a good amount of neck-deep water. Many soldiers drowned as a result of the amount of gear they were carrying and the fact that the beach was more heavily fortified than expected didn't help. The initial assault wave included ~30 Sherman duplex drive tanks, which were specially fitted with canvas apparatuses that allowed them to float. These tanks were swamped in the high waves and all but a few sank. So, in that first wave, things went like this:

-Bombing runs and artillery bombardment miss or have little effect

-Higgins boats and DD Sherman's are launched

-confusion leads to some soldiers being delivered to the wrong sector, Sherman's sink

-troops disembark at sandbar into neck deep water under much heavier mortar and machine gun fire than is anticipated

-first wave reaches the beach, and is pinned down due to intense fire and heavy fortifications that were not expected

When that first wave reaches the beach, the long day at Omaha begins. Radio contact with the troops on the beach is poor, and spotty. Many of the SCR 300 radios, the backpack ones, are ditched before the troops make it to the beach to avoid drowning. The soldiers that get there with their radioes intact soon either find that the water has messed them up or the radios actually get hit and knocked out. The handheld radios lack the range or correct frequency (can't remember which) to contact the ships offshore to call in fire support. The engineers tasked with clearing mines, obstacles and Belgian gates lack the equipment (since so much was lost or ditched in the water) to do such, and lack the communications to call for more. The troops have no tanks, lack the means to call for fire support and are in and out of contact with the commanding officers offshore. Essentially, all that can be done is feed more men to the beach and hope they can fight their way off. At one point in the afternoon, Omar Bradley considers evacuating the beach, but at this point progress is beginning and around late afternoon the troops are finally able to fight their way off the beach.

TL:DR: Prior to the assault the allied planners didn't realize how heavily defended the area was, and when the bombardment and bombing proved ineffective, it set the stage for the nightmare that followed. Confusion, deployment of the troops into neck deep water, poor communications, lack of fire support and lack of armor then contributed to the heavy losses inflicted.