"I'd be interested in a recommendation for that (external soundcard for linux laptops)."

I have a Lenovo x61s (s/h £180, best laptop I've ever had) with an RME Hammerfall (v.1 [s/h £150]).  It's great - stable, easy to setup, 8IO + the software HDSP_conf/mixer works well (and seems to have done for years).  Firewire via pcmcia card:  Got to love redundant technologies.