Concerning point 1, You don't state whether it is an OS drive, or a Data drive you hav encrypted, but for these purposes I'm going to go ahead and assume it's a Data drive as you said you have to put a password in
Basically, the only way you would lose the data, is if you both
a) Forgot the password
b) Lost the recovery key
The recovery key basically works in the same way as the password, if you did forget the password for whatever reason, you would have to input the recovery key which would then unlock the drive. From there you could change the password, (may or may not need to be decrypted/reencrypted can't remember)
Of course if the harddrive failed you'd lose it anyway.... but that's gonna happen if you encrypt it or not
Concerning point 2: Actually, Bitlocker will let you do it by default on any drive apart from the OS drive without a TPM, if you want to know whether you have a TPM, then the quickest and easiest way to find out is:
Open computer and right click C:
Click Turn on Bitlocker
Bitlocker will now check whether you have a TPM,
This is where it gets a little confusing, back in the day, By default it would not let you do it without a TPM, you had to unlock the option in Group Policy, however I just tried it, and it let me, eeven though I am pretty sure I haven't touched the option.
So basically, it will either, refuse to do it, or it will do it but only give you the option of creating a Startup key, if it exibits ANY other behaviour (IE gives you more options), then you have a TPM,
You can cancel the screen if you don't want to encrypt it by the way