The way I understand things, after WWI the armed forces were pretty well liquidated as terms of surrender. So that would leave a lot of former soldiers without jobs. By WWII Germany was mobilizing its forces. Could these former soldiers re-enlist if they so chose - or were they called back to service? How easy/difficult would it be to return to the armed forces after being out of the service for so long?
Hi there. Soldiers who served in WW1 certainly did serve for Germany in WW2. The majority of the interwar (and WW2) officer corps had served initially in WW1. Many of these officers were demobilised due to the limit placed on the German armed forces and later returned when Germany rearmed under the Nazis. However, between the war, many of these men found employment leading Freikorps battalions, although these groups became less important as time went on. Some also drifted into paramilitary groups such as the SA.
As for enlisted men, many also joined the Freikorps. Most though if they hadn't become officers would have been a bit old for initial deployment. However as the war went on many would be called up as man power became more desperate. Many of these men ended up serving in various battalions, mainly on the home front (eg. As guards of concentration camps and other facilities), although as the war came closer to Germany many did end up seeing action.
First of all, Germany had conscription - men were required by law to serve, so there was very little voluntary enlistment - most awaited their conscription orders.
As /u/Bonnieprince writes, most of the officers' corps had served in ww1.
Lower level soldiers consisted mostly of younger classes, and ww1 veterans would be at least 38 years old when the war broke out, and many would be even older. When Germany started to run out of manpower, such men were mobilised for garrison, local defence, technical roles and other non-frontline combat roles. The Volkssturm militia had many ww1 veterans in it when it was called up in October 1944 to help defend Germany.