Marriage between US citizen and Congolese refugee?

No special paperwork.

She is eligible for naturalization after having been a Green Card holder in good standing for at least 5 years. That's the standard.

There is a fast path for spouses of US citizens, and that's after she has been a Green Card holder for at least 3 years AND, in addition, being married to the same US citizen spouse for at least 3 years.

Since we don't know how long your bride-to-be has been a Green Card holder, we don't know which will come first. If she had her Green Card over 2 years now, she will hit the 5-year resident mark before you've been married for 3 years.

IF she is entering US as a certified UNHCR refugee, and will obtain her own green card prior to marriage, she must reside in US for 5 years from date of green card issuance before she might qualify to apply for naturalization. Your marriage has no effect on any legal permanent resident's residency requirements, etc.

You'll need a marriage license of course. But if she already has a green card you won't have to do anything to secure her permanent residency (because she already has that). It won't take YOU any time to get her citizenship because you won't be involved in that. She'll have to apply by herself for naturalization when she's eligible. You're trying to assume some mantle of control and authority here that is both unnecessary and perhaps should be a red flag to her that you're a bit controlling. 

Ask on a Congolese message board, then.

I'm sure you won't find anybody here who is familiar with Congolese law.

I assume you'll be moving over there . . . right?

Actually it all depends on how long she's lived here.

Dr Fiona Hill who recently testified in Congress is a naturalized citizen. To be naturalized you have to live here legally for 7 years I think. Part of it also consists of taking classes on American history and civics. Then passing an examination of it.

Or at least I think that's how it's done.