few questions about my marauder build

ok well im working on a hardcore marauder that i made it to 20 with so far and i plan to use this skill build for(its just a starter build that i plan on expanding when needed)

http://www.pathofexile.com/passive-skill-tree/AAAAAgEAAnEEsxRNGS4ZhRo4JKon7TbpOthQUFRJWGNZ818_Zp5yqXy7fNmMz5BVogCnhKyqud3AGsWKxtjUj-Nq51LsOO8O8B_yL_ZI-tI=

and i want to ask some questions.

1) im using infernal blow-added fire damage-weapon elemental damage at the momement and am loving it and im wondering is there any combination i change it to that would put out more dps?(i need to have easy access to it im not rich, and also my just incase getting that close isnt that viable i use ground slam but dont have any support on it)

2) with said skills and build what would a better weapon be a staff or 2h mace? im currently running a staff as for it gives highest dps i can find atm and wanna know what i should be looking for as end game items/passive skill nodes to pick up/

3) if i should stick to my currently used main spell(infernal blow) what other supporting gems would help out and where could i find them because i cant afford to buy anything and i dont use any quality gems anyways so oh well dont need to find one thats quualty.


also sorry my grammar and that stuff is bad.