airberlin topbonus - Couple questions from an AB virgin

I'm BA silver (OW Sapphire) and need to fly to NUE from London, though FRA would be acceptable but less convenient. AB flies LGW-NUE direct which would be great as LGW is my most convenient LON airport. Before I jump in, I have a couple of basic questions:

1) AB seems to charge a £15 ticket service charge on their website, which is not part of the fare and can be avoided by using e.g. travelocity.co.uk. Any downsides to booking on travelocity?

2) Am I right that everybody gets a free checked bag?

3) Am I right that I can't preselect a seat? Does anybody know for sure if only AB's own elites have this benefit?

4) AB flies from LGW north terminal, same as BA. I presume I'll be able to use the BA galleries lounge?

The alternative is LCY/LHR-FRA on BA, which would get me quite a few more avios but not enough to sacrifice the convenience (AB is also a tad cheaper).

TIA ^

I'm BA silver (OW Sapphire) and need to fly to NUE from London, though FRA would be acceptable but less convenient. AB flies LGW-NUE direct which would be great as LGW is my most convenient LON airport. Before I jump in, I have a couple of basic questions:

1) AB seems to charge a £15 ticket service charge on their website, which is not part of the fare and can be avoided by using e.g. travelocity.co.uk. Any downsides to booking on travelocity?

2) Am I right that everybody gets a free checked bag?

3) Am I right that I can't preselect a seat? Does anybody know for sure if only AB's own elites have this benefit?

4) AB flies from LGW north terminal, same as BA. I presume I'll be able to use the BA galleries lounge?

The alternative is LCY/LHR-FRA on BA, which would get me quite a few more avios but not enough to sacrifice the convenience (AB is also a tad cheaper).

TIA ^

1) if you can get it cheaper, do so. may result in less milage though.
2) yes
3) check w/ your TA, or pay for on AB website
4) yes

In response to 1), I have done this before. It was about 6 months ago and it was through a US site, but I assume the principles are the same. No problems whatsoever, the only downside appeared to be that I could not pull up the reservation on my iphone app (because I had not booked through their "comfort log-in" which is tied to the app.)

I think that you should be able to select seats for free (I got seat assignments on an award flight booked via BA.com) but you might have to call to get it done

Thanks for the replies! ^

I went ahead and booked on expedia.com with no booking fees. I can lookup my booking on airberlin.com and ba.com. Manage my booking on ba.com says I'll get zero avios and tier points, even though my booking class E should earn 10 TPs and 25% avios per their chart... not that it matters much.

airberlin.com doesn't let me pick up a seat for free (though they seem happy to let me pay for it), for such a short flight not really a big deal, I'll check-in early and get what's available.