I sent you a friend request. I've always been a xbox junkie so I don't have many friends on PS4 that play, unfortunately.
I'm still not familiar with all the lingo.
I think I've accepted the vanguard bounties. Are the number of these limited?
I got one about a weekly heroic or nightfall, but I'm not sure I'm able to do those yet with my rank??
What's a faction?
There are 5 Vanguard bounties and 5 Crucible bounties a day. Some are easier than others and they are worth varying amounts of reputation and marks. Marks are used as currency to buy things from the Vanguard and Crucible guys in the tower. Save marks and don't spend any until you get enough reputation to reach Vanguard/Crucible Rank 2. At that point you can buy legendary armor. Rank 3 for weapons.
There are three factions, and they basically replace the vanguard/crucible rank. You join one by finding the representative of that faction and buying and equipping a class item from them. While wearing that item, all reputation will be applied to that faction, rather than vanguard or crucible.
If you don't play a lot of competitive multiplayer, I would just rank up Vanguard rep first. If you do a lot of coop/singleplayer as well as crucible multiplayer each week, then it will be quicker to join a faction, since vanguard and crucible reputation is applied to it. So you are ranking up one faction, rather than vanguard and crucible separately.
Once you get Vanguard/Crucible/Faction rep rank 3, you will get legendary items in the mail every rank-up. I'm about to hit Vanguard rank 3. I'll have to see what I get in the mail. But I'm most excited for the ability to buy a legendary primary weapon with my Vanguard marks.
Just play through the story to hit level 20. Daily heroic story missions are basically just replaying a story mission with modifiers active that make it more difficult. These are level 22, 24 and 28, I believe.
Weekly heroic strikes are replayed strikes with heroic modifiers active. These are pretty hard. They are level 22, 26 and 28.
Weekly heroic strikes are all level 28. You cannot die on these. If your entire fireteam dies, you are kicked out of the strike. No checkpoints. These strikes offer the best rewards of any strikes. Pretty much guaranteed something legendary.
Hope this helps, but this will all become more apparent once you reach level 20, which happens quicker than you think. Bounties are going to be the quickest way to level both XP and reputation until you can do the daily and weekly events.