Fleeting Spell is good for removing battlefield control when it gets in the way. Quicken Spell is good, but I'm not convinced on Extend - you can use a cheap metamagic rod for low level spells.
By level 13 you shouldn't need combat casting. Off int (including headband) and level you should be ~+20 which auto-succeeds on level 3 and lower spells & you've got the teleport from your school to get out of the way. Add in other items and the check becomes even easier.
Rime Spell (or Chilling Amplification) is handy for battlefield control. I've never been convinced that counterspelling is a good idea; YMMV.
With Spell Focus (conj.) you could easily pick up Augment Summoning if you were so inclined.
Um. There are a lot more cold spells than sleet storm especially by 13th level. Fire shield (cold flames), frost fall, cone of cold, cold ice strike, frigid touch (load this in your spell storing armor), elemental aura, wall of ice ... not all of these are naturally BFC but add rime spell (and/or lingering spell) to them and that can change.
Treantmonk's guide was written a while ago, remember. Extend Spell was one of the best feats in the core rulebook. More has been published since; I'm not sure metamagic rods were in Pathfinder when he wrote it.
As far as counter drain goes, remember you have to spend a point from your arcane reservoir to try the counterspell, and you only get a payoff if you succeed on the dispel check. On 3rd to 5th level spells you get back the point spent at best, and on 6th-7th level spells you'll average about zero spent (-1 if failure, +1 if success). You can't counterspell 8th-9th level spells yet in this way of course and 2nd and lower don't trigger counter drain.
It's certainly possible to dump charisma as an arcanist. It does limit you to using consume spells once per day so conserve your arcane reservoir points. OTOH you start with 9 at the beginning of the day and if you burn a 6th level slot via consume spells you get 6 more, so you don't have to conserve them too carefully.
And yes, those feats/exploits should help you do a reasonable selection of things with your magic. Quicken Spell is one you're missing though, and it's probably more useful than any of the metamagic feats you have taken. Two spells per round is a very useful trick.
Meat shields are a kind of battlefield control, blocking movement. You might not need augment summoning if that's the only purpose you plan to use them for, which would free up a feat. Or you could drop selective spell on the basis that you should have enough spells with different areas prepared to be able to avoid hitting your friends. Persistent spell is a keeper IMO.
You can take each exploit once only unless it says otherwise. Metamagic knowledge doesn't say otherwise so you can't take it multiple times. That isn't a problem though because you'd just be trading one feat for another without involving the exploits.
Looks good. Your saves before spells or items will be F+7, R+8, W+6 so make sure you do get those items (cloak of resistance +5 for sure, likely also a cap of the free thinker, stone of good luck, pale green prism ioun stone.)
Cloak of resistance +5: 25 000 gp
Cap of the free thinker: 12 000 gp (reroll failed mind-affecting save 1/day)
Stone of good luck/luckstone: 20 000 gp (+1 luck to saves, skills, ability checks)
Pale green prism ioun stone: 28-30 000 gp (+1 morale or +1 competence to many things)
You probably won't want all of them but there's nothing stopping you getting any of those. None is even close to 70K gold.
A glove of storing probably isn't necessary. You can put a wand or two in spring loaded wrist sheaths, which cost 5 gp each rather than 10 000. The wand of infernal healing can go in the haversack for after combat, and the wand of cure serious wounds is probably a bad idea - too little to be useful in combat, too inefficient to be useful after combat. The silent spell rod is one you only get out when you're sneaking around and you might as well carry the still spell rod in hand when you're expecting combat assuming it's for casting in a grapple.
If you get a ring of freedom of movement you might as well not get the still spell rod.
A lesser metamagic rod of extend spell isn't a terrible idea for use with long term, low level buffs.
A few potions for the familiar to use when it's off pilfering might be useful.
I think the wand of magic missile is made at caster level 1 if my maths is correct - if you want it at all then you really want it at CL 9. Even at that level it's mostly obsolete at 13th level.
A couple other items which you might find useful.
Tunic of careful casting (5000 gp) - +2 concentration.
Amulet of natural armor (2000 gp * AC bonus squared) - bonus to AC via natural armor.
Depending on what exactly you get the cap of the free thinker might be within your budget.