For 1 ... there are two approaches to this problem.
With very fast network connection between computers, you can practically create a network share on the render computer (or create a iscsi hard drive) and load the files directly from the render computer. You edit your project and when you're done, you copy the project over to the render machine and load the project on that computer and hit render.
A deviation from this would be to create proxy files, for example for each file you plan to add to your project, you create a 720p or lower resolution file encoded in some very fast but high bitrate codec. You edit your project using those files, you save the project, and then when you move the project to the render machine you edit the project to work with the 1080p or 4k files you have.
LinusTechTips does something similar .. they have 10gbps network between editor computers and their storage servers and when they start working on a project, they copy all the files in a folder and an automated program starts processing them and converts all content regardless of resolution (1080p or 4k and codec avc standard or xavc-s or motion jpeg or whatever) to cineform (they wanted
DNxHD but it was buggy) 1080p which has a high bitrate (probably something like 80-100 mbps) but has the benefit of being decoded in hardware by the video card and that it's sort of intra-frame, meaning editors can just randomly in the timeline and they get almost instant jumps to particular frames. With other codecs, when you jump somewhere, often the codec has to decode a certain number of frames before reaching that particular frame.
The 10 gbps network is fast enough that they can stream 100-200 mbps continuously from the storage server almost as if the content is local. Also, the cineform format is supported very well by both premiere and davinci resolve (which they use for noise reduction using dedicated video cards, for color correction, gamma, overlays on green screen etc)
Regular 10 gbps network cards are still relatively expensive, probably about 130-150$ each. Gigabyte is planning to release a 10gbps network card that's supposed to be under $100 when it launches (very soon). These work with regular Cat6a cables.
There's a new standard 802.3bz (or something like that) which makes it possible to create connections at 2.5gbps using plain cat5e or 5gbps and 10gbps using Cat6a - there may be in a few months cards tat could do up to 5gbps for way less than $100.
Alternatively, you can find on eBay network cards taken from dedicated servers removed from production, which can do 10 gbps or even 40gbps, but they have optical ports, they don't have the regular RJ45 ports which would allow you to use Cat6a cables. You can make a connection between two such cards using a direct attach spf+ cable, which varies from around 20$ to $100 depending on length, for example a 3m cable would be around 40-50 dollars.
So you could have a direct connection between your computer and the render computer at 10 gbps, and you could have a separate 1gbps network card to connect to the internet router to have internet and access other machines. It's very easy to force the operating system to route all the traffic between two IPs to go through one interface (the 10gbps network card) instead of the regular 1 gbps network card.
These network cards with optical ports can be found for as little as 20$ but there's a catch ... some don't have drivers for anything higher than Windows 7 or Windows 8, or the drivers only install on Windows 2008 or Windows 2012 (the server versions of Windows) ... but often you can force Windows 7 or Windows 8 to load the server version of the drivers or you can find "hacked" drivers. With Windows 10... I don't know.
Here's an example of such cards :
link and here's an example for
a cable that would work to connect 2 such cards
See this playlist for some networking ideas:
https://www.youtube.com/playlist?list=PL8mG-RkN2uTxvguQ0LitLak61lA9jYANWSee also this: