KTSpudnik,
I also suffer from seasonal allergies but it was not a problem during the medical exam at MEPS and I did not lie on the any of the paperwork. I boldly let the doctor know that I suffer from allergies and that I get a stuffy nose every now and then. He didn't seem to care much about it though and let me pass on that. What kid of allergies do you have? Is it something extremely serious or just the sniffles every now and then? From what I have heard in the past, unless it's a life or death situation and there is no medication to control the condition, you should be fine and if you are on medication then you might have to get a wavier. So, I don't think you should be too worried.
As far as PLC is concerned, it was not what I had expected. The priors in my platoon said that PLC-jrs was nothing when compared to boot camp. But, keep in mind that PLC-srs is much harder and you have to find the motivation in yourself to graduate seniors.
After about the first week we usually had either one Sgt. instr yelling at us or the Plt Sgt at one time. We almost never had more than one of them at a time except during humps and PT. Also, there are no push-ups at OCS for screwing up. Instead, you get to do some BS essay, like "The difference between a plt sgt and a sgt instr". We had a whole bunch of those.
As far as tips go, one thing I can not stress enough is to label everything you have with your name. They will show you the proper way to label your trash and make sure that you use the laundry bag you get and also label that bag. Also, when our staff picked us up made us dump out all of our trash on the ground and seperate the civilian trash. I'm sure that every out plt had to go through the same thing but the point is that have your stuff seperated the night before so taht your trash does not get mixed up with someone elses trash. Take plenty of zip-lock bag's with you, take all the boot's you have, and I didn't take any with me but take some asprin or something. They will tell you to dump out any medication that you might have on your person but just slip it in your civilian bag. And of course, take everything you OSO recommends. The only other tip that I can think of would be to not give up, no matter what happens. I screwed up bad in the beggining but I learned from my mistakes and made a big improvement and earned the staff's respect. As my OSO told me before i left for PLC, "The key to graduating OCS is to be physically fit, don't lie/cheat/steal, and most impoerant of all, do not give up". Goodluck buddy.