@revelette1,
Of course Iran is involved in Syria. Iran supports Assad because Assad is an Alawite, a sect more closely aligned with Shia Islam. Across the ME there are populations of both Shia and Sunni Muslims with Iran supporting the Shia and Saudi Arabia the Sunni.
There's another proxy war going on in Yemen, with rumblings in Shia majority, but Sunni controlled, Bahrain, which is also an American naval base.
Both sides have their own militant groups, Hezbollah are Shia whilst Al Qaida and IS are Sunni. Overall though the Shias tend to be less extreme. Given the choice I'd rather be taken prisoner by Hezbollah than IS.