LTC mining rig - can you please answer my guestions?

Hi,
I'm thinking of building a GPU rig for LTC mining. Can I ask you a few guestions?

1) Does LTC mining require (benefit from) good CPU, or I can use the cheapest single-core available?

2) Does mining benefit from more system RAM? Is there some minumum per rig or per card or other recommended metric?

3) Is it required to insert GPU for LTC mining into pci-e x16, or it works without loss in slower ports like x4 / x2? (~Does mining use a lot of bandwidth?)

4) I see motherboards with up to 7 pci-e slots in shop. But mining rigs usually have 3 or 4 cards. Why is that? Because of best hashrate/money ratio? Or motherboard/system can't handle that much top-grafic cards at once? Because of heat control or PSU limits?

5) Internet connection minimum requirements. Is there any recommended minimum on speed/latency? For example if I use GSM to connect miner etc...

6) Is there any good complete guideline for setting up a rig (not just hundreds of posts in forum)?

Thanks for your time.