I feel like this hardly touches on the main issues. It really doesn't matter what % of the company you are given, there are tons of other factors (such as the class of stock) that can effect your future dilution, as well as the value of the options independent of dilution (for instance if there is a right to repurchase your options are worth significantly less because there is a huge risk component added to them). TLDR: it's your responsibility to understand the agreement you are signing. If you can't, you need to give it to someone impartial who does and can advise you.
Also, re: #3 after 90 days (3 months technically) the SEC eliminates many tax benefits you get from your options being classified as ISOs, so while extending the time you have to purchase is helpful, it's not like it's as simple as giving you more time to exercise. Many things change after those 90 days that have nothing to do with your company's policy.
Not sure what you mean about class of stock. Almost all employee options are common stock. Good point about repurchase rights. I should probably add a section on that. On the 90 day issue, usually those ISOs are converted to NQSOs after 90 days.
Also, re: #3 after 90 days (3 months technically) the SEC eliminates many tax benefits you get from your options being classified as ISOs, so while extending the time you have to purchase is helpful, it's not like it's as simple as giving you more time to exercise. Many things change after those 90 days that have nothing to do with your company's policy.