Let's go one by one:
1. Percentage attacks are for people who suck at math. Still don't see what difference they make otherwise
2. Attack only: kinda defeats the purpose of a team game if you can't help your teammates
3. Transfer only: because who needs bonuses after you finish plowing the enemy together
4. Those are the default settings for gift cards
5. 1 start allows for faster and more concentrated building, therefore a more fun game.
6. If you didn't want to join a simple "no thanks" would have sufficed
Dude, I am trying to help you out. Clearly you have no idea why those settings exist, which is holding you back. They allow you to do conditional orders.
I might use percentage attacks more than anyone I know. Lets say you have 11 armies on a spot, you do some delay moves and split attack the two opposing spots bordering your 11. You could just send 5 and 5, but if they attack you and reduce your stack to 6 or less, the second 5 will never happen. Instead, send %50 and %100 and you'd end up sending 3 and 2, thus the split still worked.
Another way to use percentages is send %99 at a spot as transfer only (another reason to allow transfer only). Then later do a secondary attack at %100. What that allows is that if the transfer fails (they hit your spot first and take it), then later the %100 attack goes through. If the transfer worked, you'd have nothing into the %100 attack later. There are all sorts of ways I use % attacks, despite lots of very good players I know saying it is basically not used.
I've already told you a use for transfer only, but it is used MUCH more beyond that, team games or not. If you don't know you have first move, you don't want to send a smaller stack into a large one. You use transfer only to make sure you don't waste armies.
Attack only isn't used much IMO. But you could use it with % to do a conditional move like I did above. Maybe your teammate is attacking a spot. If his attack fails, you want to hit it also. But if he does take it, you want to send your armies in another direction (maybe the opponent could run parallel). Do attack only %99, then later move another way %100. This allows you to hit there if you get first move, and if not then you can hit where he moved parallel.
Gift and start settings are a matter of opinion. But to say the advanced attack options are a waste is plain ignorant.
Edited 4/14/2015 00:15:15