Problem with some english words

[CarnivorousJelly]

1. avaiable or available
2. optimized or optimised - either one will do
3.
Should means:
- you're supposed to/obligated to do something (I SHOULD do my homework, but I want to finish SOMA)
- indicates that something is probable (Seven hours of sleep SHOULD be enough for me to not feel tired tomorrow morning)

Shall is meant to express intentions (I shall do my homework tonight, I shall also take the dog for a walk) or as future-tense (next week, I shall be in Germany).


I was going to include some other words that I've seen spelled wrong quite frequently by non-native English speakers, but I honestly can't remember the word right now, just that it involves adding an 'i' where there isn't normally one.