sie hat = she has; sie haben = they have; Sie haben = you have (formal)
Notice that the verb conjugate changes according to the subject. 'Sie' also changes to capital when used formally as 'you' (not 'they' as you have said fordhogan). All verbs in German conjugate differently according to the subject, if you are confused during a lesson hover over the verb and select 'conjugate'. Duo will then show you the different ways that verb conjugates.
Nope. They are pronounced exactly the same. One nice thing about German is that pronunciation follows strict rules. I can't think of any heteronyms (http://english.stackexchange.com/questions/198897/what-are-words-that-are-spelt-the-same-but-pronounced-differently) in the German language.