Does upvoting other peoples content affect you in anyway at all?

Yes. It reduces the amount of voting power you have in a specified time period. The best advice is to limit your upvotes to 10 or 11 100% votes per day.

It also gives you a small reward for curating. This reward is in Steem Power and accumulates as you grow on Steemit.

What is the recommended amount of posts per day to succeed here on the platform?

At least 1 per day, no more than 4 per day.

What is the best time of day to get the most upvotes?

This depends on what your posts are about, what languages you write in and who you interact with on Steemit. Many people seem to agree English language posts around noon GMT tend to do the best.

What kind of content does the best?

Content you have a passion for will do the best. If you write about things because you think they will be popular, you will be lost in a flood of other "popular" posts and end up with very little, if any, of the reward pool.

What's the fastest way to grow on the site?

Interaction! Read and thoughtfully comment on other people's posts. Get involved on Steem.Chat, look for projects, solve people's problems and MOST OF ALL DO WHAT YOU LOVE!