id these sf stories… [Dynamics of Cats]

Ok – I’m crowdsourcing the internet, because the google has failed:

there are two science fiction short stories that I need titles and authors for, source in anthology or collection would be better still.

1) humans in slower-than-light spaceship set out to colonize planet identified around nearby star. When they finally get there, they find the planet already colonized by humans, who had left after them but on a faster (ftl?) spaceship and arrived before them

2) humans expand around galaxy and find no intelligent life – finally contact is made, arrangements are set up to treat with aliens, and it is quickly realized that the aliens are the other edge of the human expansion through the galaxy, coming around from the other side, with some genetic and morphological drift

Yes, I need this for Actual Real Science, not just my own amusement