I've been wondering... What are the arguments for keeping the Electoral College? It's probably the least democratic voting system I can think of.

The arguments are Republicans still want to get voted into office. Which is the same argument behind every single anti-democratic policy.

Georgia is now down to a difference of 463.

If it was based on the popular vote, the Reps would almost certainly rarely win again 

The electoral college wouldn't be quite so bad if not for 3 things that make it the absolute worst:

1. Winner-takes-all in almost all states. If there were a proportional system or at least a highest averages system in place which would split up the vote of any state proportionally between all the persons running for office, it could actually be somewhat decent.
2. The 3 electoral votes minimum per state, which gives states with a low population way too much power as it currently stands. Doubly so as the electoral votes are calculated proportionally and then added 2 votes on top for everyone instead of doing it in one go, which further reinforces smaller states.
3. The fact that you only vote for electors, which are not obliged to follow the people's vote.

Also, as far as I know, the electoral college is enshrined in the US constitution and thus exceedingly hard to get rid off.

My proposition for a temporary solution would be to expand the amount of electoral votes from 538 to something like 599. Not only would an uneven number help avoid a potential nightmare of having both candidates with the same amount of electoral votes, the expansion would mostly go to the bigger states and thus lessen the influence the states with a small population have by a lot and thus strongly weakening the impact of point number 2.

If you remove those three aspects, it would not be an electoral college anymore, it would just be popular vote but with the final numbers divided by x.

People just don't like change. IT's not about what's right vs what's wrong, it's about what's easy. Changing how they do voting can and would take a lot of work and have a lot of growing pains, and as we've seen in this election: Take the devil you know over the devil you don't. 

It would be a regional breakdown.

It would also bring one of the few advantages of something like the electoral college: that you could have regional parties which would go under in a national vote, but get some seats if you have a fixed allocation of seats for each state.

I'm reviewing Joe Biden's promises to get an estimate of how hard they would be to realize with a republican senate and Mitch Mcconell still as the majority leader.
My initial though, and from what I understand of US politics, is that it will be extremely difficult but, if I'm correct, budget may be used to bypass the Mcconnell "gate" to some degree.
From what I understand, Mcconnell can't really hold budget from votes and even if republicans turn the budget down forcing a shutdown, Republicans tend to end up "losing" shutdowns most of the time https://www.youtube.com/watch?v=4pITlnrvhrY

I'm using this article as a listing of Joe Biden's promises : https://www.sfchronicle.com/politics/article/Here-s-what-Joe-Biden-wants-to-do-as-president-15709583.php

Ending the pandemic:
The easy part should be to increase testing.
The hard one would be to pass any relief package as they will be blocked by Mcconnell.
A mask mandate may be possible but might sow division and fuel right wing activist and conspiracy theorist.
It would probably be necessary to work directly with every state and ask them to follow science and mandate mask to avoid sowing more division.
On this file though Joe Biden will inivitably be able to claim victory as vaccine roll out.

Expanding health care:
Near impossible, but what's in place might just be properly funded with next budget.

Reforming immigration:
Near impossible

Raising the minimum wage:
Difficult but may bypass Senate by working directly with states to raise their minimum wages and include provision in the next budget to help states and/or business to which this burden might be to much.

Stronger action on climate change:
Hard part - would be to add new regulation and law.
The more "doable" part would be to end fossil fuel subsidies and increase investment in green infrastructure and Green program in the next budget.

Free college — for some:
Can be done to some degree using the budget.

Higher taxes for the rich, corporations:
Doable - if his able to tied those in his next budget.
Since Trump tax cut included an increase for 2021 for those earning to below 40K and the pandemic will likely still be around it should be doable to force a vote on a new tax plan.

I agree mostly but at the very least on Immigration he can reverse some of the executive orders that Trump had made and reinstate some of the ones like for Dreamers that Obama had in place before Trump removed them.

On the Environment, it be hard to make new laws but the Environmental Protection Agency do have some power to regulate so Biden simply putting someone in charge of the EPA that actually believe in the EPA mission instead of someone who there to undermine it will be a improvement.