hi tasharil, all I am going to say comes of my own experience with shoppers, and maybe its not the only way to raise a shopper.
The three different chars I raised as shoppers are High Elf, Temple Guardian and Dragon Mage, the best choices are the chars with bargaining as primary skill choice(HE, DM and Inquisitor), cause you need a strong char to reach niob the faster the better.
I recommend to reach niob in single player at level 80, in multiplayer a bit higher, but once you reach niob you may stop leveling up with him/her, because bargaining is less efficient the higher your level becomes, I ve downloaded a lvl200 shopper with 630 bargaining and he barely sees anymore a yellow item in merchants. So my recommendation is leaving your chopper at level 120 or 140 max, higher level means less yellow items, but your shopper will be able to support chars up to level 160, which is not bad.
I have to say that bargaining becomes a tiresome routine at higher levels, you will need to spend much more time to get nice jewelry or items, so to make it more efficient I recommend you to use, if possible, a different shopper for each class, simply because 70% of all the stuff offered in merchants belong to the shopper's class.
About your questions:
1. It depends what you are looking for, I always recommend +skills and +ca in the same amulet or +skills-+aspect if you are playing a single aspect, if you are lucky enough you will find amulets with the same bonus twice that means at level 25 you may find an amulet with +2 all skills or +8 at level 85, but there is also a very small chance to find amulet with +all skills and +bargaining or +all skills and +general skills, these are the best stuff you can find for your shopper gear
2. Best options are in general mutation sets, Velaria's Garment, Halgrim's Legs, chestplate and shoulders of Lumen's Servants, if you are lucky enough to see a helmet/belt with +bargaining and +general skills one of them twice that is the best option for it, better than any other set item in general, for dragon mage I recommend 3 set items of same aspect set, you can go with 6 so you have +all skills first bonus twice and halgrim's legs gives you a decent amount of +all skills. About relics, best option is having a low level char in niob, not a shopper, to buy relics for you shooper still in gold or plat. Dual wielding two Officer saber or with Kufferath Defender is no doubt the best option.
You will need of course a smither to support your shopper foring all items with amulets, if you can have 22 or 23 sockets forged with amulets with double bargaining and/or double +all skills then your bargaining level will be easily 3 times your char's level.
3. Best place for shopping in my opinion is in Thylisium at the entrance of the Inquisition Temple, there you have a merchant and a runemaster next to the entrance to the sewers, use it to reset merchant, its faster than teleporting with portals
4. Best shopper in my opinion is Dragon Mage due his set bonus, but Seraphim and TG are also good options because they got more armor pieces than others.
Forgot to say that you need a ratio 3:1 at level 85 and 4-5:1 at level 110 (bargaining:char level) not only to get decent stuff from merchants but also to see less white and more yellow items. Otherwise if you cant have a nice gear your shopper will be useless before level 120, so I recommend updating gear each 5 level if possible to not decrease your ratio too much
Edited by Daniat, 23 August 2015 - 06:07 PM.