I'm going to try this for you but i want other members to jump in here and correct me please:
1. Is the PE8 stated above too heavy, should I go for a lighter line (PE 6 / 6.5) to try and get a longer cast?
You already have a long rod which should aid in casting longer distances with the right technique so perhaps try using PE8 and if its too much for you; change down.
2. What type and strength leader should I use? Should I make these twisted leaders I've read about, if so what strength leader should I start with? OR should I just go with the conventional (non-twisted) leader (80lb or 100lb)?
For a beginner i would use a twisted leader system so its really easy to change and requires no knots!
Easy:
3. What are some brands of leaders you recommend? So far I was considering Xzoga Taka SK as I love their Takalon monofilament.
Fisherman Super Stealth is the only thing i've personally used for my heavy tackle fishing.
4. How long do you make your leaders? Does the connecting knot between the braid and leader sit outside the end guides when casting? Also what knots do you recommend? Do you have any tips to quickly and freely change between lures without having to cut up or re-tie rigs that can be timely?
I make my leader knot sit between the reel and the stripper guide or between the stripper guide and second guide; weather its an FG knot or using a twisty leader i do the same and i make the 'drop' as long as needed to cast well; this will take you some trial and error. FG knot is a good go-to and 4-turn uni for terminal tackle attachments.
5. Any recommendations on lures / poppers to start with? So far I've acquired a couple Shimano Ocea stickbaits 185 mm / 85 g (got them on special) which I've set up with the Baker rig (Owner SJ-41 and Shout Kudako hooks - I don't go cheap on hooks!).
Get some River 2 Sea Dumbell Pops in the largest size or Halco Rooster Haymakers in the largest size for the cheapest options for poppers; upgrade the hooks. There are too many cheap popper/stickbait brands that i have time to list so perhaps some others can help.