The Moon is so bright you could observe it just fine, it's so bright there's little to match it. In the past I've also observed Jupiter and Venus from my driveway as they're bright also, and if you just throw on a hoodie you can shield yourself from much of the street lamps.
I've no experience of the Seben barlow, but depending on how much you have to spend, I'd suggest a GSO Barlow from Andrews (for example). The GSO barlows are excellent for the price, I used to have the 2.5x before I got my Baader. Quite light too.
I can't help with collimation unfortunately as I use an SCT but hopefully someone will chime in
Congrats on your find, can't beat a good book