a) I can not figure from where the number 1.05001234BTC came you said we have 10 mixed UTXO with each UTXO with 0.1BTC so total is 1BTC or I am missing something
You forget 0.05001234
BTC which isn't mixed
isn't mixing about using all of the mixed coins in a single transaction or more than a transaction ?
As @fillippone mentioned, that would reduce your and other's privacy, so the answer is no.