exchanging pieces

I’ll try to answer these for you:

1) If the pieces are equal value, then it should be okay to trade them, but you should always think about the position before the trade and after the trade; choose the one which favors you more. Usually, you’ll want to trade pieces (not pawns) when you have more material and you’ll usually want to avoid trading pieces (while trading pawns) when you have less material. This is because the side winning wants to simplify to convert into a win easier, so the losing side should try to complicate things if they can, so the winning side messes up somewhere and gives up their advantage.

It’s also worth mentioning that all pieces have relative value. A good starting point is the piece estimates of pawn = 1 point, knight = 3 points, bishop = 3 points, rook = 5 points, queen = 9 points, but there’s some positions where pieces may feel less or more valuable. For example, maybe an outposted knight on the sixth rank is so amazing that you don’t want to trade it for an inactive rook. Maybe an equal trade of bishop for bishop isn’t as good for you because your bishop was developed and they haven’t moved their bishop yet. There’s a lot of complications when deciding anything in chess and this is partly why chess is a difficult game to become extremely good at.

2) I don’t know if I understand this question. I think you’re asking if you have some piece that’s trapped or basically doomed, is it worth saving it, or just leave it there. If you can save it, then try to, but if it’s actually trapped, then you’ll usually want to take as much material as you can with it. If you can’t, then just leave it there and at least your opponent “wastes” a move on capturing it and probably “wastes” another move to return the attacked piece to a more active square.

I have lots of chess videos, but since you asked about the trading, I’ll share one video about the bishop trades you should be aware of: https://youtu.be/C6PuM9Z44sc?si=GFHJogtHLs0ZXv5D

As stated above, there are a few important things to know about trading.

First of all, it is absolutely important to note that "equal" trades aren't always equal. A well-placed knight can be worth as much as a rook, whereas a bishop that's trapped behind its own men is pretty much nothing more than a pawn that's stuck to one color and also moves backwards.

However, that's not the only way trades can be unequal. Sometimes a trade can result in openings of lines that greatly benefit one player while severely hindering the other. For example, take this position from one of my games:

Bad trading is a typical beginner error.

In general, if you take a piece, you almost always will give your opponent a chance to activate their pieces.

Thus never ever trade, unless you actually get something out of it.

For example if the opponent blundered the piece and you get it for free, sure you can "trade".

If you get also a pawn with the piece, thats likely a good trade, too.

If you can get a rook for your bishop or knight, thats a great trade.

If you have a piece thats meh, like a bishop of the color of all your own pawns, and theres a good piece the opponent has, like a knight on a great outpost, thats a good trade.

If you can get a bishop for your knight and now have the bishop pair, thats a tiny advantage, so thats a maybe.

If you have a great outpost for your knight and you can trade your opponent down to nothing but a bishop of the wrong color, thats a great trade. That may force your opponent to either trade a rook for your knight, or to suffer a crushing and possibly terminal disadvantage.

Depends.

Depends on the position.

Depends on the position.