You have/will probably read what we were thinking out loud on irc, but I'll post it here for the sake of having it all in one place.
First, I'd like you to forget any sort of physical damage and leech. It just wont' work. Even if you go all out damage on your setup (might merc + LoH + CoH etc) you will end up with like 52 leech per hit on minions of destruction, and they have 50% block. It's not worst ever, but it's not anything reliable and you should really not focus on it.
You will absolutely need cta, if because of anything, for merc. He will drop dead each and every time he encounters any dangerous aura or any pack of not so friendly monsters. Especially if you don't have that much control over him (and you don't cuz no teleport on demand). CtA will be must. You cast BO, swap with beast in inventory and go on. I don't really think this should be open to discussion
Another thing that shouldn't be open to discussion is merc setup. You will want Infinity, beta Delirium and Holy Freeze. Armor that compliments him best is CoH for resists, good damage and leech. This will make your fragile character into crowd control monster that shouldn't die unless you are drunk.
Anyway, you still have option to go with maxblock and PB (4fpa/6fpa decrep) or caddy vita one (5fpa/7fpa decrep).
From quick glance I'd favor maxblock setup but it's your choice in the end.
Maxblock:
Helm: Dream
Amulet: 2sorc/10 chance to block craft (fcr, dex, other nice mods are nice)
Weapon: 6os PB with 5 x ress/IAS jewels and Shael (5fpa)
Armor: Guardian Angel (Cham, 5/5 light facet)
Shield: Dream Tower Shield (best block)
Gloves: 1.07 LoH (20IAS for 6 fpa under decrep)
Ring1: BKWB (RF if no Cham armor)
Ring2: BKWB (10 fcr if you want to keep 65 fcr switch, probably good choice unless you have beta BKWB)
Belt: Arach
Boots: high frw and whatever compliments your build best (high ress, MF, noclue)
Beast/Spirit switch, cta in inventory
With GA and ctb amulet you will need only 208 dex for block at level 95. It seems reasonable and it allows you to use PB. 208 dex should provide you with enough ar to whack most things under conviction without needing to focus on ar. Vita setup will have more problems with this. Besides, you still want good attack rating because mercs being mercs often wander outside your range and you can't quick tele to get him back without reshifting. If you use RF, you won't need much/any cold ress at all. With 50% fire sorb of LoH you won't need much fire ress, but it's still not advisable to tank wave 4 head on unless you have some FR at least.
With GA max 15 to all ress you can hit 90 allress but I think it's going overboard. Your PB will have 5 os to play with resist/ias jewels and with dual dreams having avg 25 allress, still having boots slot open and small charms, you should be able to get 90 LR and probably one more resists that you think might be crucial (I'm mostly looking at PR). 40 fbr on GA will lower your block from 12 to acceptableish 8 frames.
If you get hax 2sorc/10fcr/high ctb amulet you can even use secondary fcr ring while keeping 65 fcr teleport switch.
Charms should be mostly lightning skillers for damage or vita/ress charms if you need some safety. Balance is up to you. No fire plz. Check Baal monster resists and immunities. Light is only way. Especially gg would be sparkling/7frw charms in both setups.
Vita:
Helm: Dream
Amulet: 2/10 fcr with usual useful mods
Weapon: Griss Caddy 3 shael, ar/IAS or ress/IAS jewel
Armor: 1.07 ark whatever socket (defensive) +20lsd/-20elr/100life/30LR armor (ofensive)
Shield: Dream Kite Shield
Gloves: 1.07 LoH
Ring1: RF (one Ravenfrost is must or your ar might suck too much even with infinity)
Ring2: BKWB
Belt: Arach
Boots: high frw and whatever compliments your build best (high ress, MF, noclue)
Beast/Spirit switch, cta in inventory
You might want to add some attack rating charms or you might end up sub 2000 attack rating overall. Not sure how crucial is ar with conviction, but you might not always have merc around you like I said probably 10 times already, so getting some ar here might not be bad idea. Rest of the charms like above.
I added offensive armor option just because, but if you want more durable char, you might want to go SoJ RF Frostburns, and some split between energy and vitality to have decent ES. You will have massive life from Arkaine's and beta cta already so dumping some points into energy might not be worst idea ever. This works nicely with your warmth providing nice mana regen, but you would need to socket your Ark with IAS/something jewel to keep 7fpa under decrep.
Optional skills might be Orb + 1point CM for LI/FI lister, ES/TK in second setup (don't like it in first cuz you'd already waste lots of points into dex for block), chilling armor, Thunderstorm for helping you chase those last few skeletons around, SF for quick cast before starting whacking monsters etc.
This should cover you for now. When you decide of vita/block and your wealth level, we can try and optimize her with what you have available and ready to spend on her