As far as I know re. created players in career mode, when you start a career it loads the default squads, so your player wouldn't be in the warrington/leeds/wigan etc squad. There might be the option to change this but I haven't got round to creating players yet...
You can pick your line-up, as with any rl game, before any given game, but signings are only at the end of the season afaik. If signings before playing is really important to you, you could always sim an entire season, which would probably take about ten/fifteen mins cos it's really quick between games (unlike fifa for example) you just tap x a couple of times and you're at next week's game, simulating my entire pre-season took about a minute...
The game is such an improvement on rll1, the stadia look fantastic, the commentry is a slight improvement (alhough I die a little inside when the co-commentator mentions elvis..)
Be prepared for a frustrating first hour though, take everything you know about playing an rl game and forget it, the controls are completely different, I spent my first game putting grubbers in every time I got the ball because i thought it was the sprint button.