With regard to Thomas I will echo what others have said.
Firstly, congratulations to him for a very good 6 Nations debut. Secondly, if he does choose to go to Wales to help his international career then I will be very sad as he is a superb player for us and up there with Lauchbury as our most important forward (in my opinion) but I will wish him well and have no hard feelings what so ever. In fact I will always look out for him and root for him when not playing us (much like Guy Thompson).
However, he is with us next year, which is great. In all honesty we've got enough problems at the moment without wondering who will be here in two years time.
Also I'm not sure how many caps he will get for Wales even if he goes. Their No7 factory is superb. Tipuric is still only 29 and a great player (also a superb lineout option which is a rare asset in 7), Ellis Jenkins (26) is one of the best turnover merchants around, Ollie Griffiths (24) I haven't seen much of but there was a lot of chatter in Wales about him being the next Warburton, James Davis (28) is also an excellent player at the breakdown and linkman, and Josh Navidi (28) has been very good in every international I've seen him in. So Thomas has a big fight on his hands. Add Faletau, Moriarty, Shingler and Wainwright and I'd be surprised if Thomas made the WRC squad.
On Jack Willis, he started out as a 7 (hence his twitter handle I think) and was used by England U20s as a 7, interchanging with Will Evans if I remember but he seems much more of a 6/6.5. Big, powerful, decent in the lineout and competes over the ball when he knows he can/will win it rather than scrapping for everything on the deck and slowing ball up as well as winning turnovers (cf Tom Curry's last couple of games).