A 2wd will have front axle and hubs that are much smaller and simpler. 4wd front axles will have a big "ball joint" knuckle that the drive axle goes through, and a planetary compartment visible inside the lug bolt circle visible in any photo. Just the tread on the tires and the bolt pattern will identify the 4wd axle vs 2wd. Having a driven front axle DOES NOT mean it works, that's a common failure, and easy to not notice. A 2wd loader is extremely limited working in soft, greasy, or backing uphill situations. Getting around is not a problem if you learn how to use the bucket, and backhoe to pull around.
As far as avoiding high pressure fuel systems, there may be certain years you'd want to avoid, but avoiding newer in general is not a sound strategy. A lot of people would try to avoid certain years of emissions also, which translates into what different companies tried to do to meet those emissions and resulted in more or less reliable systems. If you're not afraid of computers, it's not hard to get the equipment to handle that yourself, just most backhoe "hobbyists" don't and would rather avoid it.
Everything I've needed for JD has been available from my local JD farm dealer (green dealership), they just can't look up parts, but they can order anything they don't have, and they have, or had most in stock. I'm not expecting in stock service, or to have them have knowledgeable techs. The yellow dealer might not have anybody that knows the old tech either, hit or miss with either of them.
