u can do dungeons or rdf at low level as rogue but treat it as 'side gig', the main focus should be the yellow/red quests to level. since u're a pvp player then solo leveling as sub wont be a problem at all. focusing on dungeons to level only effective if u're a tank/healer. without friends/boost, focusing on questing is much better imo. besides when u hit 68 u will find northend quests are waay more effective than spamming dungeons.
if u see buying instant 80 worth the coins then buy it, as for gearing fresh 80 there are many guides online or post like this here :
https://forum.warmane.com/showthread.php?t=426653 as reference.
but heres the way i do it as fresh naked 80 without spending any coins:
-take minning and herbalist, make a castsequence macro to track herb and minning nodes. farm them and sell them with undercut prices.
-use the gold to buy boes to fill all your gear slots with cheap 187ilvl or 200ilvl blues, u can buy caster gears aswell. the catch here is to gear it enough to do heroics asap with minimal gold spent. u can fill them with pvp gears with honor aswell by doing weekly quests at wg or do rbgs.
-do heroics to get some upgrades and emblems, u can continue mining/herbs to get the 264ilvl boes, in your case they are ikfirus chest piece, bladeborn leg, wodin's neck and footpad of impending death. its not necessary but great gearscore boost if u're planning to do raids. it will come in handy to boost your gearscore enough to atleast VOA where u can get pvp gears from. u can do icc rep farm too, if u need the 277 ashen ring it wont take much time anyway. but doing raid means u need to have pve talent, better to focus on having a pair 232ilvl daggers from fos pos and hor heroic, or nighttime axe from fos hc. u can use the hit and ap pvp trinkets (34k honor points each). or u can do toc 5 n trinket farm for banner, and/or use gold to buy darkmoon greatness trinket. i prefer buy the pvp ones cz less hassle and u wont do any serious raiding yet anyway.(P.S. u can sneak rowan riffle on your ranged slot to boost gs for voa req, its cheap!)
-after u get furious set gears and the rest pvp gears, u can decide whether u spend some coins for bis pieces or continue the grinds for upgrades with serious raidings/arenas.