It is depending on the action you make. According to Steemd, the approximate RC (Resource Credits) costs are the following:
But the approximate costs for posting is not mentioned. Maybe that costs the same as the commenting.
The recharge rate is depending on how much Steem Power/RC (Resource Credits) you have. My current recharge rate is 24M per day. My current RC (Resource Credits) are 97% (114M/118M). 100% recharged in 3 hours.
RC gets charged at 20% a day, meaning 5 days to reach 100%. Your 100% RC will differ from someone else's because RC is tied to your SP. The more SP you have, the more RC you have. While the nominal charge might be different between everyone, the % charge will be the same.
To calculate your exact charge per day, just go to steemd.com/@yourusernamehere, scroll down to resource credits, and take the number after max_mana and multiply that by 0.2. All actions have a fixed cost(as of writing this answer) thats the same for everyone. So the more SP you have, the more RC you have, the more you can be active.
I think this really depends on the amount of Steem Power a person has. Usually a person would have his/her resource credit charged really rapidly if their SP are quite high. Once you have lots of SP then your resources credits get recharged quite rapidly. Mine is currently almost unlimited as I have about 315 SP and after I've done with lots of the different activities on all the various dapps on Steem, by tomorrow it gets to full bar again. I used to have resources credit problems and I had to wait for the resources to go up when my steem power was quite low, i had to wait around 4 days per time for my resource credit to get recharged.
Once my resource credit grew a lot as I converted a lot of my steem earlier on into Steem power, it slowly grew quite a lot till now I don't really worry much of this. Now the next thing after that, is that I usually participate more and more to make sure that my reputation keeps increasing. I have been working a lot on this platform daily. I do understand the feeling of not having enough resource credits as that's what I faced earlier about a month ago. I had to wait for many days before being able to participate again which was kind of a long wait if your really keen on participating.
I think you can get delegation for steem power but I am not sure how that works yet at the moment of time.