Fair warning, not a PvPer, but i listen to them a lot so pick things up. I'm sure a PvPer will be along soon to give you the real deal and correct any errors i make.
First thing i will say is PvP can be a bit of rock, paper, scissors. There is the "meta" that can change with time as people discover new techniques or FD make changes. So, let's imagine the current meta is to run heavily kinetic resist shields, becaue the meta says people should use kinetic weapons. So you do that, and then you run into someone running all lasers... ooops.
Of course, in big ships you can usually fit enough modules to get high resists across the board... with a lot of engineering.
And i think that has to be the first thing that is stressed, if you want to be competitive you will need to do a lot of engineering.
On to your questions:
1) Yes, there are. The main one is known as CGI (Galactic Combat Initiative), you can google their Discord. Personal recommendation, i don't like it, although probably the best place to get advice. Salt levels are off the scale there. Personally i'd recommend the PvP Hub (again google it). Salt levels are much lower. However, its not so much designed to to educate people with direct advice, but to help people find PvP duels, solo and wing. But people there tend to be decent and will offer advice. FD also run the Galactic University where some PvPers i think hang out. Not sure how useful it is for learning there, but some good PvPers did used to hang out there. Two other Discord PvP groups i'm aware of are Cobra Kai (i'm a member) who are focused on being the "good" guys, protecting people and running interference against bad guys. And the Alliance PvP defense force (forget the name actually) who protect the alliance through PvP. There are many others though.
Check out this thread:
https://forums.frontier.co.uk/showthread.php/253560-Public-Elite-Dangerous-related-Discord-servers
2) AFAIK, high resistance is still the meta. Although i guess it depends on ship and loadout.
3) This is one of those rock, paper, scissor issues. But many (most?) PvPers do carry SCBs, and without something to stop recharge you are going to be facing some drawn out fights.
4) Tricky one. I'm going to go with no for PvP. AFAIK, most decent PvPers use fixed weapons, so chaff is useless. Higher tier players are very good at hitting targets as well. Also chaff can be used as fixed by deselecting the target while chaff is going. And if you are flying a big ship, then chaff isn't so useful anyway. Maybe on a small ship, but then you usually need those hardpoints more.
5) Again, back to the meta and RPS. I'll leave this one to those who can speak more authoritivly on the topic.
6) They can be quite good for taking out external hardpoints once shields drop. However, if your opponent is carrying PDTs then you might just be wasting hardpoints. I've seen a few PvP vids with people using them. PvPers tend to prefer pack hounds, as PDTs struggle against them. ECMs are rare as far as i know, beause they are tricky to use i think, but those i suggest are the hard counter to pack hounds.
7) Very much depends on your build and ship really. Basically those sorts of questions are best left for when you are talking about specific builds. However, beams are tricky as they produce a lot of heat and PvP ships tend to run hot with the requirements for dirty drives, often requiring overcharged PP to power things like SCBs and SBs. I think this is one reason PvPers tend to favour kinetics sometimes. There is an engineering mod that allows beams to dump heat... as long as you hit the opponent.
8) Very much depends on what sort of build you are going for. Personally i enjoy a huge cannon with force shell to play pinball with ships, but i don't think that is recommended for PvP. By the way, as you say "my huge hardpoint" (singlar) that implies you are considering using either the FdL, Anaconda, or Cutter. Fair warning, the Anaconda is probably the worst of those 3 for competitive PvP. Cutter is a fat cow but can shield tank very well. The FdL is very popular for PvP. Overall though, you need to say what ship you are considering for specific advice.
9) Not always. Not all PvPers bother with chaff, so can be good against those, and you can always unlock the target if you are good without it and use them like fixed. You basically trade ToT for raw damage. However, the ToT usually more than makes up for it, as long as your opponent isn't chaffing. Meta says fixed though.
10) PvP battles tend to be long drawn out affairs when both opponents are equally matched, so i'd say the most important ones are those that shorten the length of battles. So feedback cascade is an obvious choice. Having corrosive on a weapon (ususally a MC) is also good for getting hull down quicker.
As I said, keep in mind i'm not much of a PvPer, and some of my advice might be lacking.