1) Will a good PVP build be able to last for PVE purposes too? It seems to be that way from what I understand in-game and out-games.
Yea, usually if you're solid against other players, the monsters that are around your level shouldn't be too much of an issue for you :p
2) Partied with various fighter / bdef and comparing those non-luck(NL) and luck(L), it seems on average that NL deals a higher basic dmg and L types deal higher max dmg. Am I wrong on this?
I suppose it depends if I prefer stability over randomness (seen L types when non-crits, dmg drops quite massively) I don't have the luxury ATM over getting good gears and lapis etc so I reckon I should not go for L-Builds?
If you're taking this warrior to 80, then build some Luc while you level up. Once you max your Buffs "Concentration" and "Bash" together they give you 40% Critical hit bonus. So you realistically only need 275ish which at level 70/80 you'll get from gear naturally (perhaps one or two fortune lapis) so at level 80 the crit's will come very easily.
3) I read that for L-Builds, it would be better to restat at later points. So in the early stages I was thinking of 2Dex /2Rec /5(+1)Str per level? It would work out to 158Dex /158Rec / 395Str (+79) at end-game. I thought of increasing my hit rate and HP ever so slightly; i noted that fighters dont actually have good def and hp to really last long.
For bdef I did think of doing about the same (-1 Rec, +1 Str).
If you're just going for leveling, going 2 rec would make you a tougher opponent, but if you invest more into STR You don't really need to last that long, just my opinion. A nice balence would be 2Dex/1Rec/6+1 Str. You may even want to consider not investing in rec after a certain point if you feel you're getting tanky enough.
4) What about def against magic attacks? Do i need to consider that? Magic users thou dmg high, seems to be squishy unless that are full REC etc (then their dmg drops).
This is where Wit lapis comes in. Your helm should have Wit 6/7 which gives you +175 resist to your character. Unfortunately its not really viable to build any more, considering how squishy magic users are, you'd be better off building strength or dex to smash right through them.