Mount:
EQ6-R seems like a good option. Or something similar in capacity and price from Ioptron.
You could go the ZWO route and go for their new AM5, but this is so new, that there isn't much information yet on its performance, and it's a bit costly compared to others.
Scope:
One thing to keep in mind here is your camera. the 294MC has quite large pixels.
Pixelsize determines what focal length is best suited to be used. Simply put: if you use a very short focal length with large pixels, the stars and details will be smaller than the pixels and you don't have enough pixels to capture the details. Or if you're using too long a focal length, you're using "too many" pixels to capture those details, meaning you might have to expose for longer to get enough detail and light into those pixels. So the range you probably want to stick in with the 294MC is about 450-1500mm, (you can go higher for planetary)
I'd consider getting 2 scopes as usually 1 scope isn't enough to do both DSO AND planetary, there isn't a 1 trick pony out there.
As most DSO's work great at <500mm, but planetary requires 1500mm+. And being in the middle of those 2, usually means you can't capture a full nebula in your frame.
Closest to the one trick pony would perhaps be a Celestron EdgeHD 8, with the Starizona Hyperstar conversion on it. This gives you both the 1600-2000mm for planetary and the 400-ish mm F2 scope for DSO in one. It probably is the closest you'll get to having 1 scope doing it "all" - But, it's not as easy to use as normal refractors/reflectors. So, as a beginner this perhaps isn't a good starting point.
So I would suggest 2 scopes. to cover a range of focal lengths.
The shorter focal length ones have a huge selection at the 400-500mm mark. The Skywatcher Esprit 100 is very good. But might leave less of a budget for anything else after purchasing a mount+ the esprit.
As for the long focal length, most APO's will get very very costly. So you're probably then looking at Newtonians, Cassegrain, Ritchey-Chertien scopes. Usually providing high focal lengths, decent aperture and good bang for your buck. Skywatcher, Celestron, Omegon, TSoptics, loads of brands have good options here. - Or you could go for a Maksutov design, they tend to be very cheap, but are only really useful for visual and planetary - while the others would also allow you to image galaxies.
Don't forget that most scopes will need field flatteners or correctors. Some can be costly.
Cables:
wait till you have everything set up. And then start measuring how long your cables need to be, especially on the scope.
Often the camera's and accessories come with 6ft long cables that you don't always need. So.. investing in a bunch of 1-2ft cables helps a lot to get rid of a lot of the clutter.
Filters:
Quad, tri, dual band filters are the way to go for a colour camera.
Antlia makes a dual band one that is getting good reviews. Optolong makes the L-Enhance/L-Extreme ones that are great.
Loads of other manufacturers are of course available. Also, get a more "wide" filter. something like the L-Pro, works great to get some "real" colour on moon-less nights.
Also, consider going a size up on the filters. Right now you might be fine with 1.25" filters. But, consider possible upgrades.
Maybe you'll go for a ZWO ASI 2600MC/MM in the future, then you'll need 36mm filters. It is possibly worth biting the bullet now and sizing up now, instead of having to buy filters now, and new filters again in the future.
(I could have saved quite a bit of money by future-proofing my purchases a little more)
Others:
Don't forget that all the "other" bits and bobs cost too.
Adapters, rings, Barlows. Filterwheels/drawers, Dew heaters, etc.
You also may want to consider things like a Electronic Focuser,
Software:
consider using a part of that budget for pixinsight. It's very powerful with editing astrophotography. I've been able to pull out more of my data with pixinsight than photoshop.
