What will happen to our existing BTC? Can we still use those? Will those be of no use?
- At this point it seems likely to me that the BTC chain will survive a hard forking attempt by BTU. Really, except for an impressive hash rate it seems to have almost no other support.
Will the price of BTC rise or fall?
- Both. Probably not at the same time. Who knows really.
Will the price of BTU be same as BTC?
- No. Most likely they will be freely traded against each other.
Can we convert BTC into BTU?
- After the split, the same coins will exist on both chains at first. After disintermediating them, you should be able to sell one for the other, if both have sufficient buyers to maintain any sort of price greater than zero.