Don't get this the wrong way, but if you have 4/700 you are not better than average. You might have more experience than average but your mechanics are clearly not that great. Not trying to insult you, but that's the first thing you have to admit.
Even if you get teamed on in every single deathmatch you play, an above average player should have more wins than that.
For the deathmatch situation, people will random team, that's how it goes, especially if the two of them are understacked compared to you. You can't really change that. But if you want to lower the chances of that happening, try to stay out of their way, keep it on the low and come in at the right moment. If you happen to have a pair of diamond boots or a diamond helmet, take it off when you guys get teleported back to spawn, try not to show your sword at all, don't give them any information, whether it's better than theirs or worse.
I think that FOV should be at around 100, but it's ultimately a personal preference. I play at around 95-105.
FNS is a huge part of SG, you HAVE to utilize it if you want to win more. Practice quick FNSing, practice the 360 fns, practice every type. As someone said above, it is especially useful against teams. And don't worry about not spamming it, spam it if you have to, it can win you the fight even if it does make you look a bit silly.
BOW is over powered in my opinion, if you aren't good with bow, get better with it, you can win more games than you are currently winning using ONLY your bow (provided that you are good with it). Imagine combining it with your other resources. I hate bow spammers as well, but you have to adapt. What's the saying, "adapt or be extinct"?
I don't like playing defensively either, I'm all about the plays. But you can't be like a bull and just run into a team and expect to win every time. Tease them, but in NO CASE, unless it's for money, if you know what I mean

, should you sweat your ass off just not to lose the game. NOBODY likes those players, if you see that they are good players and they aren't falling for your FNSs, choke points etc. , I suggest giving up and moving onto the next game, you are just wasting everybody's time when you could be winning a different game. Yes, there are instances where you can kill good teams, of course, but in my opinion it is not worth the time you have to put in.
The rod is another key part, it is my favorite item and I don't fight without unless I have to or I'm super confident. Very strong item and if you aren't very good at rodding people, get good at it, there's not much else to it really. It can create many, many opportunities.
While playing to get better, you will obviously get better and eventually develop a feel for these things. You will know when to rod, you will learn how to run better, when to stop, when not to, what fights to take etc.
As someone mentioned above, maps are a big part of it if you are worse than average and trying to get better. If you are trying to go from average to above average, or to a god's level, maps should not make that much of a difference. You should be able to handle/adapt to every situation you get put in.
Watch people that you know are good, analyze their playstyle and their decisions. And learn to love the challenge. After you get to a level where you think you are good enough, start doing challenges, most of them (if not all of them) put you at a disadvantage which I think is crucial to improving your game.
No no no no no, I always do that, that is the way to become a god at this game. The stronger the disadvantage the greater the satisfaction.
I think that should cover it