Yes to the RT1200B trimmer.
No to the dillon primer filler, at least not in my opinion. I have 10 primer tubes. Takes about 2 minutes per tube to fill up and I set them aside in a little wood rack I built. I seem to need a break about every 500 rounds or so, so its a good time to re-fill primer tubes. I guess I cant see my self needing to spend $300 on the primer tube filler. Maybe you can. IMO, dont get it now, but maybe think about it in the future.
As far as the trimmer, yes get it for rifle brass prep. The Dillon die is a bit tight in the neck so there are 2 ways to "solve" this. One is to send the die out and have it reamed a little. Most shops can do this. The other(the route I chose) was to get a 21st Century Shooting mandrel neck expander. This sets your neck tension PERFECTLY and helps your brass concentricity. My 223 prep tool head is setup like this: Lee universal de-prime, swage, empty, empty, trimmer, empty, 21st Century Mandrel neck expander. Everything accomplished in one pass. My trim die is the only die I use for full length sizing, I dont have a "traditional" full length die on the machine. Lube, run through machine, tumble to remove lube, bam, ready to load brass. And get the Lee universal de-primer. Its WAY more stout than any other die I have tried. Get a couple extra de-cap rods as they are $2 and also mess with the tension on the unit as they are VERY tight from the factory and wont slip, they will just bend the rod(ask me how I know LOL).
As far as how to buy the machine. You said you are using 100% SPP 45 brass. DO NOT buy the machine setup for 45. Buy the machine setup for .223 so you get the small primer setup, one less thing to buy. The 1050 does NOT come with both primer setups like the 550/650 does, you have to buy it and its not cheap. So to convert to 45 you will need: tool head, dies, powder thrower(I like a separate pistol and rifle thrower instead of messing with changing powder bars), conversion kit(shell plate, buttons, backup swage expander, colator wheel, case feed adapter, etc...). Only thing else you will need(and I dont know if BEnos has them) is the backup swage expander die body($20 I think) plus the special lock ring(I think its a 5/8's or something). You also will want to make sure you have a separate powder through die and activator for 45, which I dont know if they are included with the powder thrower or not(most likely NOT). Brian can make sure you get everything, but like I said, I dont think he stocks some of the small parts, but Dillon is fast at shipping.
As far as spare parts, if you order from Dillon order a few of the advance pawls and springs, they are like $3 a piece, but if they bend or break, the machine is out of commission. The advance pawl is just cheap stamped steel and bends fairly easily. I think I am on my 4th or 5th on my auto drive machine, but that thing gets a lot more abuse. Also get a second tool head main spring, I think they are $15, but again, if something happens(they have been known to pop out the side) the machine is down. The only other springs that have been known to cause issues are the primer springs, but I think they are good for 25-30k rounds. I dont have spares, but will probably pick up a spare or two next time I order from Dillon.
Then come the accessories. A lot of people swear by the bearing for the shell plate. I dont have one and honestly havent felt a need. The final 2" or so of handle throw controls the advance. You can run it smooth and not have issues. Others swear by the plastic ball a guy on ebay sells to replace the metal ball, I dont know, my metal ball seems to work fine. Some will say clip a little off the detent ball spring. Again, mine seems to be ok from the factory and runs fairly smooth. I do have on my brass prep dedicated machine the little spent primer tube a guy sells on Brian Enos for like 15 bucks or something that you hook a tube up to and then feeds into a bucket(I use a little 1 quart paint can from homodepot). I need to get another one for my new machine. There are a couple places that sell tool head stands. I bought one from the same guy that sells the spent primer tube bracket. Its ok, its a little flimsy when trying to put a tool head on that has a trimmer. Next one I buy will be from somewhere else. Somebody makes a metal one, another place makes a solid plastic(delrin maybe) one that looks a TON stronger. There are plans on Brian Enos for one you can build out of PVC pipe.
Let me know what other questions you have and I will try to answer them. Most of the questions I had, I found answers to on Brian Enos.
ETA: if you can mount your press on the edge of your bench, rock on. I wanted mine mounted a little bit back so I had to notch my bench for the handle. Wasnt a big deal on my bench, but might be on yours. Inline Fabrications just released their 1050 mount that raises the machine up slightly and SHOULD(I dont have any direct experience, but if you call Dan he should know) allow you to mount the machine back from the edge and not have handle interference.
