hi! your question is quite complex so let my apologize for this wall of text.
Let's start with a litle premise: dont play choppa alone. If you dont have dedicated guard and healer you will die countless time and it will be very frustrating. choppa have one of the higher sustained damage in game and can generate alot of pressure but it need to be babysitted. to properly play the Choppa you need to learn three skills: positiong, rage management and target selection. without the firsts two no amount of healer and tank will keep you alive. without the 3rd skills your gear and your level will be completely irrelevant.
as you can see choppa is hard to play but i assure you that it can give huge satisfaction.
what i say now will work mostly in case of WB vs WB, but it have a general valence:
theoretically as a choppa you are shock infantry and your role is to break the frontline and hit the healers/rdps but actually if you try to charge in the middle of the blob (even if guarded and healed) you will just melt. so you need to use a bit of cunning (hard for a choppa, i know). stay always behinde your guard (Hold The Line will save you from a lot of fireball and other nasty ranged shyt), use Git To The Choppa as opener to kill someone before the real engagement, dont overextend and play safe until you have a clear comprehension of the situation (the moment you exit from guard range you will melt), dont stay in the middle of the blob and try to hit the side, use the terrain to gain coverage from ranged attack and always use Shrug It Of before to use Charge or Flee. These are just some of the many thing that can skrew you up if ignored, many other will come with experience.
what i say now will work only if you are not slotting Wot Rules?:
to deal the real damage you must be berserker which increase your damage by 50% but halve your armor and resistance, drop your rage if you see that you are taking too much damage and if this is not enough use Come And Git It (Detaunt doesn't stack with guard so there is no point using it, unless you not guarded). try to stay berserker as long as you can without suiciding. your base ability will deal enough damage (while berserker) so think about your exhaustive blow as finisher, use it only when you are sure to kill someone. before to engage use all the ability that can buff you or your party as Chop Fasta, Come And Git It, Git Stuck In and so on.
If you are using Wot Rules? things will be different:
be sure to alway have armor pots, abosrb pots, double healing pots, double AP pots and the blessing from Gork and Mork (you will need it)
. to use Wot Rules? will higly increase your damage but will make you squishy AF. Using this tactic will let you do some nice trick like to use Chop Fata and then spam Wild Choppin', if you do so your AP will finish in few seconds so you will drink AP pots like an AP-holic, use Keep On Choppin if you finish the AP pots.
about the target choice:
avoid tank unless they are already dying or squishy, as soon a dying deftard tank reach max life ignore him, you will never take him down. try to focus on not guarded healer/dps. to see if someone is guarded use the addons "Buffhead", if you need help to configure it then pm me. to hit guarded targets is a waste of time and a risk (you give time to the enemy to notice you and try to defend with morals/pots/other things) so if your target (even if not guarded) isn't dying just switch it to another one.
gear:
for WB play the RvR one is great, the purple ring from influence is a good jewel. the midium equip will be: 2 subjogator/smugler/doomsday wapons, beastlord set (cloak, ring, pocket), full rvr set of your rr (annhilator/conqueror/vanquisher/invader) and 2 genesis or sentinel and invader.
about the talisman you should try to almost cap the strenght and reached 950 or 1000 once you done so you can chose to increase Wounds (your main defensive stat) or WS. about the RR points go for futile strike 3, opportunity 4 and the rest in parry/dodge & disrupt/ini/wounds. if you want to be more defensive skip the 4th opportunity and take more defensive stat.
build for r40/rr40 WB choppa:
RoR.builders - Choppa
usually I'm Da Biggest! is a must have but if you are so brave to try Wot Rules? this is the tactict to switch with.
about the small scale build and playstyle the are many difference and actually i dont have time to write them down, sorry