...what XP level are Rogue Trader characters? I want to start my PCs at the same level as RT PCs.

I suspect the characters in Forsaken Bounty were only given relevant skills, rather than skills that realistically the PC's would be expected to have. But in terms of pure potential, they're about equivalent to Rank 4 DH PC's.

Is that a full Rank 4?

Nope, as in newly graduated to rank 4. The thing is, the RT characters seem to have less skills and talents, but have achieved a greater degree of mastery than their DH equivalents would have by that point.

Looking at the preview for the Explorator class, the rank 1 in RT looks to be approximately equal to the beginning of Rank 4 in DH.

however it does seem that the skill focuses of the characters are very different, almost more milituristic with the "General" weapon talents.

- Raith

Ross Watson stated in the Dice Like Thunder podcast that starting RT characters would be roughly equal to 5000XP DH ones.

Well, from my brief look up of the Bounty characters, I think I came up with about 3000xp worth of advances. Of course, admittedly the skills and talents were a bit sparse or seemed combined for ease of use. Trask's dual wield talent, for example. It's shown as a single talent, but in DH to use a pistol and a melee requires both two-weapon talents (melee and ranged), etc.

It appears that the primary allotment of this initial XP is in stat increases (about 2000 of it), although this is still guessing as I don't know the actual costs for increases. I went by DH with 2x costing 100, etc , and assumed stats in the 40's (or sometimes high 30's) were stats that had been raised. I also assumed most skills and talents the PCs started with only costsed 100xp, which is typical. I added some extra xp costs, like with Trask's two-weapon talent, to reflect the purchase of the multi-talents from DH. 3000xp seemed to be about the correct amount for each FB character.

I calculated that an average guardsman starting with all characteristics around 30 would have to spend slightly over 5000 xp (5200 to be exact) in order to reach characteristics of the same level as the arch-militant given in FB according to the guardsman characteristic advances table in the DH core rulebook. Ross Watson knows what he is talking about . But this figure doesn't include skills and talents. The real truth will only be known when we finally hold the real RT in our hands.