Thinking of getting an Xbox One X and I have a few questions?

Skyrim SE looks and plays superb on the One X, just recently started playing through it myself.

1 - You would be able to redownload them

2 - Yes

3 - Just as smooth as any other version of the One really.

1. All your games are tied to your account, not a specific X Box. If the games are "yours", no worries.

2. I bounce two externals from a launch day X Box 1, to a X Box 1 S, and to a X Box 1 X, all the time. No problems.

3. With non-enhanced games you'll notice faster load times. Enhanced games load faster, look better, and are much smoother; especially over my original.

[quote user="UsR Twisted D"]

Considering buying Reach tomorrow, and have a few questions.

1) Is online play free if you buy pre-owned, or is there a one use code for online? [/quote]

All you need is to be an Xbox live gold member, there's no extra codes required.

[quote user="UsR Twisted D"] 2) I hear there is custom made maps, is this like Halo 3 where you could customize the maps or is it a complete map designer. [/quote]

It's like Halo 3 where you can edit the maps, but the new editing system is much better and easier to use.

[quote user="UsR Twisted D"] 3) Are the user made maps free to download if there is any (above question) [/quote]

The user made maps are free to download.
Here's the link.

[quote user="UsR Twisted D"] 4) What is the DLC like for this game? [/quote]

There are two map packs, the defiant one has two multi-player maps and one Firefight one. The Noble map pack has three multi-player map packs, and in my opinion has the best maps available for the game. Although, Defiant is very good too.

Defiant link,
Noble link.

I personally like both the map packs and those maps also have forge, which is the map editing tool.