I'm only in my second season of the game; but I'll do my best to answer:

1. Captain - I don't think it adds much, but you may as well put your best player there who has been there for a reasonable amount of time, like in real life. If a club sings a new best player, they don't automatically make him their captain. Also, the captain won't be the longest serving player on the club if that player is really bad; so try to combine the two

2. Preferred foot - Typically the full backs and strikers should be on the side of their preferred foot, though it doesn't really matter for everyone else. Wingers could either be on the side of their preferred foot, eg. Navas, so they can get down the wing and make crosses for the strikers; or they could be on the opposite side, eg. Hazard, so they can cut in and shoot. This does happen for strikers sometimes, but not often

3. Height - It's always nice to have some height in your team, especially on the CB's to clear the danger and pose a threat in the opposition's box. For other players though, it's completely optional. If they're smaller, they're usually quicker & better at dribbling/passing; whereas the bigger players are a lot more of a physical presence. Take Ibra and Messi as an example. Both great players, but both have a completely different style of play; and the team should adapt to what type of players you have

4. Corner & freekick takers - Corner takers can be either foot. Having an in-swinging or out-swinging corner taker is down to personal preference. Personally, I prefer the corner taker to be taking it on his wrong side, ie. a right-footer taking the left sided corners, to put pressure on the keeper. But it's not too important which way you choose.
Freekick takers however, is usually more of a universal agreement, that it should be taken by someone on his opposite side: a right-footer taking freekicks to the left of the box, and visa versa. This is because it gives them the ability to bend it around the wall and into the top corner. Although there are plenty of examples to show that you can use either a right- or left-footed player on either side of the box; so again this comes down to personal preference and ability of your players. If you had a a 5* and 2* player both with the freekick ability, but they use different feet; I would always get the 5* player to take it, whichever side


TL;DR: Basically, it's all personal choice. There is no right/wrong answer