Tier2 General to Tier 1 Ent Switch Question

Hello All,

I've been on a Tier 2 General last 2 years and I am considering quitting my job & starting my own Venture. I was wondering what the process looks like. I understand there is a GBP 200K requirement. A few questions

1. I am a US citizen and I have that money in the US. Do I NEED to transfer the money to a bank in UK ?
2. If after 1 year, I decide to not pursue the Venture, can I transfer the money back to the US ?
3. Should I register my company first and then apply for a Tier 1 Ent Conversion ? Or should it be the other way around.
4. I assume that my family can also transition with me on Tier 1 (they are currently on a Tier 2 Dependent VISA)
5. How long does the process take End to End ?
6. Is it fairly easy to carry out the conversion or is it better to seek professional help and how much should I expect to spend for 4 of us on the process ?

Thanks !
InLoveWithLondon

Also, one more question :

Does the Tier 1 Ent visa allow me to carry out some contract work on the side while I am pursuing my Venture or will I be needing to get a Tier 2 Sponsorship for that work separately ?

TIA for your responses.