I was never as big a fan of IPS for soloing as others that swear by it...as long as Archers Focus is working like it currently does, you're going to be doing a lot of damage. You usually dont want to have a whole chain of mobs aggro on you at once, anyway. Smart artis are good pullers
As far as gear at 20, the cheap "entry level" xbow is a L20 Cormyrian....2[w] die IIRC, plus 3 potentially useful mods.
The next step up would be a T3 Calomel repeater....two good Shroud procs, temporary HPs on vorpals, and you can stick in a Red augment for 1d10 extra elemental damage. A little more investment time than a Calomel, but not as much Alchemical or GS by a longshot.
You ultimately would be shooting for Needle or an Acid/Water/Air Alchemical (too many Fire immunes, and that gives you the best balance of DPS and CC), though. Needle's probably easier between the two, and it offers better base/crit damage by a longshot, but there's something to be said for all the useful mods you can stick on an Alchemical too. Acid Burst, Earthgrab, Greater Stone Prison, Crushing Wave, Corrosive Salt, Electric Storm gives you almost 27 extra elemental damage per shot and an almost 10% chance-on-hit for one of two good CC effects.
For Crafting, its just a matter of grinding out a LOOOT of gear to break down. Wait until you have like ~100 Greater Essences of a bunch of different types, buy a 5% Elixir from the Cannith challenge vendor, and spend 15 mins grinding everything out. Here's how I do my grinding:
1) Select the Essence type you want to grind with
2) Insert the Essence into the crafting station, and sort the list by XP.
3) Pick whatever gives you the best XP per Greater Essence spent. Ie, 6 Greaters for 50 XP is better than 12 Greaters for 75. Shoot for ones in the 65%-80% success chance range, that usually gives you the most XP without wasting too many Essences on failures.
4) If there's no worthwhile recipes on the Bound terminal for a given essence type, go over to the Unbound terminal, those recipes are all different and you can usually find good options on one if they're not on the other
5) When you get a buttload of Lesser essences, use them to craft Shards of Potential in whatever school you need to grind. Again, Shards of Potential on the Unbound terminal give you really good XP for a really low cost in Lesser Essences, once you can craft them.
Also, look up which Collectables are used in Cannith Crafting and make sure to keep those in your bag for grinding. Recipes with Collectable components usually give you good XP.
I usually just put a Spell Power booster of the appropriate element in my runearms. Saves me from having to slot it somewhere else, and lets you swap between runearms without having to swap out a separate spell power item too.
Other useful options will become available at higher crafting levels....if you havent taken Mobility as a feat already, then Mobility gives you 2% Dodge that stacks with everything else. Much easier at crafting L20 than Dodge 2% at crafting L100 which doesnt stack with other Insight sources of Dodge (like Bracers of Wind) anyway.
You probably already have Attack Bonus from goggles, and Blindness Immunity from a yellow augment, , and False Life from something else too, but those could all be options for LD if you dont. Ranged Alacrity doesnt stack with Armor of Speed, if you were thinking about that...
For your docent - Giantcraft Docent from GH. Ideally you arent getting hit enough for the Guard procs to matter, but it gives you a 5% extra damage buff on most kills that stacks with Archers Focus.