Two questions:

Does a player need to be on a roster to get the effects of training camp?

If so, do signings for that day's sim happen before or after training camp?

Yes, players on a roster for TC gain playbook knowledge as well as conditioning. Players not on a roster lose both.

Transactions happen before Training Camp, so you can sign a player on the TC stage and they will be on your team for camp.

Ok, what if the player is on roster but not on the DC, do they have any gains/losses after TC?

Depth chart has no impact on TC, you don't have to have that set until your first game. But it's a good idea because it will help you move players into another position if necessary, and that _is_ important for TC (they will gain experience at whatever position they are assigned to)

Ah right, I thought it was only their default position that got trained, thanks.

Yeah, I like to have my players on depth chart for training camp, specially important if you playing players out of position as depth like WLB at SLB. Every little bit helps. I try to keep depth charts somewhat deep as it will help during season if a certain position gets injuries to more then 1 players, you then have someone who still has some experience there even if it isnt his natural position

So, Morbid, if you I do that, cross train MLB/SLB.. how many seasons does it take or do you give to the cross train portion? And you don't then give gameplay to that secondary position,right? Only if there is an injury that causes the need for it. And of course this would be training your backup player at that position, right? For instance can a good enough training be had for just one training camp of doing this? I could see doing this with FB/RB, TE/WR, and of course G/T positions.

Bringing up a question; can I take a newly drafted defensive player, NT and change his position to G? (Seahawks do that quite a lot I've learned). Or does the game switches, the way it was programmed, only lose pts in that players usual position if I try doing that?

I keep the depth chart permanently like that. Every game he plays he gains more position experience. So even if he is coming off the bench just a couple plays a game his knowledge at that position improves.

Also how much your bench plays has to do with your settings for subs. During the season I keep it around 75% but during the preseason games its better to have it lower so your bench does get more playing time and thus more positional strength

I doubt switching a DT to a Offensive Line position would be very benificial as I am not sure if he really would improve much on blocking skills but jdavid could answer that one better. I have never even tried something that drastic

The best way to know what positions are best for your players is pretty simple, Just view them and go to change positions and you can see what other positions they have the best skills at.

Sometimes you might find a small LB that can play one of the safety positions if needed or aven a big safety that can play LB. Its all in viewing your players and matching their personal skills for that position. It might look like he could play the position but you could also get a false overall if you dont pay attention to his actual physical skills.

Hope that helps