Request for Advice on Video Production Setup

I use a Roland V-40HD video production switcher fed by two Canon XHA1 cameras with analog component cabling, and want to simultaneously record the video from each using a good 4:4:4 codec for editing. I currently have one of the switcher's outputs connected to a DVD recorder, but need to have high-definition archival copies. I think I will need a 4x4 router to connect the cabling to, to distribute it to the switcher and also to PC-based video capture cards. I often use supplemental video from one other camera, and am planning to add a CG input to the switcher from the PC I will use, thus the 4x4 requirement.

I want to preserve the analog component quality from the cameras for post-production use, and be able to use that PC to also live stream the event without choking or dropping frames. The PC I am considering for this task is the MSI X99A Workstation with an i7 6800K CPU, several terabytes of fast internal RAID storage, and a GeForce GTX 1050 Ti [4 GB] graphics card to use with Dell UP2516D and ASUS PA248Q monitors. Which video capture cards and software is most appropriate for what I am wanting? If they can also capture 4K video, that's a plus, but I have to maximize the gear already in place.

[moved to hardware forum by mod]