I think beerbelly has a mongolian type that throws out a decent amount of power. Bring your 4 ring along anyways, I might call around the night before or one night next week to pick up your equip (p.s. how you getting there on the day?)
I think the hop additions should be fine at 60 and 20. From what I put into Beersmith, at 60 and 20 the IBU's are a little on the low side, I was just thinking I don't want it to have too much hop flavour coming through, although it probably won't matter much as 20 mins (=~35 no chill) would be only slightly less isomerised than a 35 min. As I said, it looks like the IBU's are fairly low so I don't think it'll be a problem.
I'm not too sure about mixing type 1 and 2. Depends on the properties of each. Obviously one's darker than the other, but what about sweetness etc?
Either way, I'm happy to grab 10 keys of whatever munich (might grab a bag anyway) we need and I'll grab a kilo of carafa while I'm there... I need some of both.
In terms of gear, I reckon bring:
50L Mash tun
50L Keggle (to use as HLT)
Element
Any ingredients (you said you've got plenty of tett?)
I'll have essentially the same setup. 50L MT, 50L HLT. And we'll just both run the mash tuns into my 92L boiler and we'll use a combo of gas/electricity to boil. I have access to two circuits to keep the HLT water how with elements, so that's no problem, and I'll set up a make-shift 3 tier system for 2 side-by-side brew rigs.
Should be a good brew.