This often happens with dual battery installs, it starts off as 'I just want to add a fridge and light', then comes the 'need to jump start yourself' and then onto the winch.
Each requires careful thought, I have wired mine in (link in sig) and it works perfect, and now after 'testing' for nearly five years (I have been busy

)I am fine tuning the install. Make a decision of what you want to do now. Yes the costs will be higher initially but when you move from that fridge supply to a winch then the extra money spent on the VSR or cabling will come back to you.
So to the fuses and what the 7610. It is about the current that the 7610 and cabling can hold CONTINOUS. I am unsure of the 7610 VSR's amperage but, if it is for example 150 amps and you pull 200 for a few seconds no big deal, Blue Seas gear is some of the best around. A starter is only engaged for a few seconds and I am going to assume you are using the typical 2.2kw starter? Then you will during cranking pull an initial 180 ish amps, this will fall away as the motor starts to spin, perhaps 140 for 5 seconds and the motor starts? So the starter is no big deal but, a winch is another ball game altogether, a typical winch would pull say 250+ amps CONTINOUS, and this is where the 'wheat is sorted from the chaf' when it comes to VSR's, cabling, and fuses.
The fuse is to protect the cable, a typical fuse will hold (while heating) about double the rating, of course a dead short will cause it to blow.
So you need to know the maximum amps your winch will ever pull, it is unlikely you would be winching with the engine off, and if you were surely you would stop the winch before cranking right? So simultaneous draws do not need to be factored in, so your fuse choice is based primarily on the cable (copper not inc jacket) thickness, and the maximum amperage the winch when in good working order will pull. If the winch stalls but current continues to flow then things are going to get hot very quickly, amperage rises and the fuse blows, hopefully protecting the winch and more importantly the cable.
Spend some time on this and get it right, despite having a good knowledge of electrics I have posted on here a number of times for others opinions, someone may see something that I missed.
regards
Dave