1. Yes there are such Shop exclusive items: underwear with 0.16 physical/magical crit power (best f2p underwear is 0.12), mounts with a 2.0 crit factor for 6 sec every 60 sec (f2p 1.5, sometimes events where with extreme luck, you may get such a 2.0 mount), much higher accessability of scrolls to reroll random stats on gear.
2. As of now, I guess it´s pretty hard to get back to the end content, as the combat system grew much faster (much more attack speed), the gear upgrade chances are pretty low, all the gear has 3-6 random stats on 13 different pierces (some of them cannot be rolled but need to be dropped well). Thus its hard to get good gear and make decent dmg.
But once you got acceptable gear & skill it won´t be too hard to find groups for dungeons. (Guilds / Statics became more interesting, as the community definetly shrank the last years)
3. The pets have several skills: auto loot, auto gather (ore, plants, essences), fishing support (able to get best fish while afk fishing), self-feeding (no need to activly feed pets), auto use health/mana potion when below x %.
Also you can upgrade pets to partners. these can have the same skills as pets, but also can give you 3-40 Power and have an additional effect: higher crafting crits, higher best fish chance, give shield when hit, random restore health/mana, more exp...