I know you have made the decision to go for the progressive, but let me add to the chorus here saying it's a good idea. You will still have use for your single stage press for small batches, and loading while developing a load. I also use a single stage with a universal decapper when working with really dirty brass that is going into the tumbler right after. It keeps the progressive cleaner. Other uses of the single stage press that I have recently used are bullet pulling and case forming.
I've had problems with the priming system on my 550, a subject that was hashed over in detail in one of the threads here. I solved them all with an after market primer bearing that it worth every penny. I'll find the link to it and post it up in the next day or so.
Now, I pretty much load everything on the progressive, even rifle loads I plan on using out to 600 yard in service rifle matches. Properly run you can load very accurate match grade ammo on the progressive, just like the factories do. There is no reason to single stage pretty much anything else.
There are a lot of folks here that really know how to run these machines, so yes, do come back and pick brains. I know I did and it served me very well. I had loaded for decades on a single stage, and found there was still a bit to learn to really make a progressive shine. I've even set up a tool head that allows me to deprime, swage primer pockets, resize and once I get the Dillon trimmer, to trim progressively. All for much less than the case prep machine that Dillon is now offering.
You can also get parts from Dillon that allow any type of manual powder measure to be attached to the tool head. With this arrangement you can meter long grained extruded powder as accurately as when single loading. You do have to manually activate the powder measure, but even with this additional step it's far far faster than any other method.
I'll second (third, fourth???) the use of a Lee FCD in station 4. They are simply the best solution for crimping that I have found.
I hope this is helpful!