Hi Mark. I'll start with the comment someone is bound to make.. Find a good teacher.
That aside, here are the questions I can answer..
Strings: I don't know the wraps but someone on here will but choosing the right string is a process of experimentation and yes it's expensive.
But.. As you search the string threads you'll find some megathreads that will give you an idea about popular choices. Part of it is what works with your bass, will you be playing bow as well as pizz? and which string does your bass like.
You might start with a good hybrid string good for both or a favorite for pizz playing like Spirocores.
The BP100 is pretty simple to install. Just use the clips to mount on the bridge between the E - A strings and the D - G strings. Use of a pre-amp depends on the type of amp you have. If it's geared toward electric bass, then a pre-amp will probably be needed. Many amps designed for upright are more sensitive and the pre-amp is unnecessary.
Bridge height: Notes up high wil be harder to get. A lot of that is building your technique.
you can try lowering and depending on how well your bass is set up you may find that your strings will bottom out pretty quick.
I wouldn't worry too much about this right now. You have a lot to learn about playing down low
To conclude, I started by suggesting a good teacher. The other thing you'll want to find is a good luthier. As you learn to play you'll get better at knowing what to ask of your luthier.