You want gritty and "realistic", but do your players? Ask them. Present these ideas to them. If they like them and you like them, feel free to use them.
Personally, I would refuse. I might be willing to discuss a couple of points, but a DM who said, "This is what we're doing." would get a "Ne!" from me. I've played in too many games I hated with "awesome house rules that add to realism" to continue to waste my time on them.
I don't want realism when I play D&D. Actually, it's not even realistic. It's just "stuff that makes characters suck". I don't see where the fun will be for the players.
1. While this improves characters, it adds an unnecessary aspect of bookkeeping that they've tried to get away from. I'm neutral on it.
2. and 3. No. They only make things harder without increasing fun. Rule changes that increase fun are OK. Rule changes which don't are bad. At least in my book.
4. I was in a one-shot where a player was going to shoot a monster. The DM decided that there was a penalty for an adjacent ally. I told him that there isn't in this edition. "Well, it would make sense, so there is." My response: "No, there isn't. This game isn't about making sense. It's about fun. Telling him that you were going to shaft archery might have made him choose something different. I'm here to play D&D, not something that you're going to change as the idea comes to you." 4e isn't about screwing over anybody but the monsters. This makes range suck.
Realism isn't just silly as it is now. Realism is silly in any roleplaying game. Period. That's not to say that you shouldn't have problems, diseases, and other nasty things. But I played in a horrible game that included more rolling for saves in the first game than I had rolled in the YEARS before then. Why? The characters were in the Chuult in Forgotten Realms. They had to save numerous times every day from diseases. I've mentioned this game before. The DM was proud of his "realistic" house rules document. I'm glad that I got out of it and play with competent people now.