Editing GoPro videos in FCPX then exporting to YT

A little overwhelmed by the riches of information on the web for editing with FCPX. I am no more than a novice editor (comfortable in FCPX over iMovie). I saw no stickies or forum rules, so I'm going to cut ahead to my questions and hope any confident responses/reference links will help.

The video: a totally stuffed 3-minute video of me traveling for two months, meant to run on Youtube.

1. Frame rate mixing. My timeline is 1080p 29.97 in FCPX. I have 2.7k 29.97 videos converted to 1080p 29.97 .mov files via ProRes 422. I have also converted my 1080p59.94 files to .mov and ready for use (to avoid rendering times in FCPX). Right now I am confused: will my 59.94 videos never look that fluid in a 29.97 timeline? Will they simply never look the way I shot them again? Am I stuck with the best that these 59.94 files can afford to look in a 29.97 timeline -- or is there *any* filter plugin / method / FCPX option, which will help these 59.94 files look unquestionably better -- I read things about motion blur. There are also the Frame Sampling options in Rate Conform. Too many options, too little time. Help.

2. The best slow motion possible. There is an overwhelming amount of info as to how to get FCPX to get the best kind of slow motion from my 59ish clips. These clips have already been converted to 59.94fps in a converter. Is it, therefore, too late to attempt these "best slo mo methods" or is it worth asking what I can still do (plugins or methods) that will give me the best kind of slow motion out of the 59ish clips?

3. Exporting to YT. I read that the best method to do this is some option that says "HD Youtube 1080p" somewhere in FCPX. However, there are 2.7k clips that I have down converted but that I still want to make the best of. Bit rate comes into play here. Are there any bitrate options I have to ensure I sort out before exporting (12Mbps at least) or something like that? I am still not 100% on all these details. One last complication is ProRes 422 vs PR422 HQ. I've *already* transcoded with ProRes 422 for FCPX editing (no option for HQ). FCPX has the HQ option. Do I use it?

Apologies for the long post. Any clear cut steps for the third question (clearest export method + bitrate + codec info) would be incredibly helpful!

.... so many Qs, apologies when I miss one (most) :

Do I understand correctly you convert your sources manually, before importing to FCPX? You should avoid that. Helps to solve most of your other issues. esp. that slowmo part:

best slowmo is high framerate on record, 'slow' fps in project, e.g. 120 vs 24 ...
the other methods, namely Optical Flow can help, but never give results of 'natural' slowmo.
(older board members know my ' 5000fps ' example - that's 100fps in 25project + OF = lots of wobble in critical parts)

conc. 60 vs 30 ... spend some time on this website
frames-per-second.appspot.com

It demoes interactively the conjunction btw angle-speed/'object speed', shutter-speed and framerate.
high shutter speed + low fps results in stutter. so, many fail is done on recording, hard to fix that in post (post-motion blur never looks 'natural, made a free plugin for that, in the plugin section of this board, test it). Expecting the same motion resolution/'smoothness' in a 30fps movie like in a 60one is nonsense.

You can not set bitrates in the Share dialogue of FCPX - that asks for Compressor (or other apps, like Poor Man's Compressor, Mpeg Streamclip).
What you can do, if bandwidth is no issue, simply upload a Masterfile ... it doesn't get any better.

but, stepp #1 Do not convert outside FCPX. it 'swallows' any format, codec, framerate in any Project setting. As I like to phrase, don't try to outsmart CuperTino

And, Welcome, George, to fcp.co

Karsten, thank you for a really insightful response.

Basically, I was told that to avoid massively long render times with .MP4 files (GoPro videos) I had to convert them (isn't transcode the word?) by using a dedicated converter (payed for it, called Wondershare.. maybe I shouldn't have, but it helped), by optimizing the files to .mov by transcoding to ProRes 422. If anything, the size of the converted files was exponentially larger even though I had greatly trimmed down the clips to a couple seconds each. I think this transcoding thing was the wise thing to do.. But since you're a veteran here, something tells me that I'm missing a piece of the puzzle...?

Another thing I wanted to ask you: is the option "Automatic Speed" the exact same thing as Retiming a clip to 50% speed slow? (applying the options to a 60-now-auto converted-to-30 by fcpx).

Don't convert the GoPro files. Just let FCPX do the job. This will result in better quality footage.

Navigator wrote: Don't convert the GoPro files. Just let FCPX do the job. This will result in better quality footage.

cannot say better

All the 'manual' converting/transcoding (=same) is based upon hearsay.
Use FCPX as intended => better, faster, nicer results.

I never convert our GoPro clips, ever.

Convert, optimize, transcode, all means the same thing.

As Karsten said, the "image quality" of the original recording can not be made "better". It can only be converted to a codec that is more stable and easier for the computer to use, or transcoded to a codec that will actually loose a bit of image quality. But you can't make it "better". Can't add data that doesn't exist.

Thanks for your informative information sharing.