Hypothetical example. If someone has a Trezor T with some bitcoin and monero on it.  

1. Is this less security (from potential crypto vulns) if using one Trezor for xmr and btc, vs. two trezors one for each coin? Such as if know public key of BTC + XMR public key (or view key) from the  same Trezor it makes it easier potentially to uncover the seed ?

2. How is XMR private key derived on Trezor? Does it use the 24 words seed directly or does it use some sort of deriviation seperate from BTC?

3. If Alice uses trezor for btc and xmr. And if hypothetically the xmr private key gets leaked by some weakness, is her btc on that same trezor at risk also?