Massively confused about bottom brackets and cranksets! Help brother out.

I've just bought a Langster frame and need a bottom bracket and crankset, but the choice and properties of them are overwhelming. Chainline, spline length, Square taper, JLS, sealed, externalc cups - too much for me.

All I want is someone to hold my hand and tell me it will be okay.
Or alternatively please advise me on what is the de-facto choice for a lightish yet durable BB and CS suitable for a 2009 Langster. I'm looking for something easy to install and maintian that 'just works'.

I like the look of the SRAM 300S courier. Anyone comment?

Also what special tools will I need?

Chars...

Someone will come along with the long answer shortly no doubt but I'll just do reassuring hand hold and say that the S-300 will work and work very well with very little fuss. I've been using mine for seven years daily and have no complaints. That said they RRP at about £100? If so consider spending the extra £25ish to get a set of forum favourite Omniums from Bike24

You'll need some decent grease for the threads and BB tool like this, but it's a very installation - getting the old BB out of the frame maybe not though. Also if not already removed, it will probably need a different BB tool like this as it's not external cups.

Edit:

Should you get stuck at any point there's also the Mechanics and Fixing subforum where you'll find loads of useful information.