1. How many hours was it till I unlock stuff? After 9 hours you'll get everything. 4 hours to get the first unlocks
2. Will it say a message when I do actually unlock things...? No, however you can always check the Secret section in Records.
3. I remember hearing it was like...4 hours or something to start unlocking songs...do I get them all at once? The unlocks are like in groups. Here's the complete list
4 hours= Hidden Options
5 hours= Hidden AC songs
6 hours= Hidden Pop'n GB songs
7 hours= Hidden CS songs
7.5 hours= Other Hidden Characters
8 hours= Hidden Courses
8.5 hours= Hidden ee'mall songs
9 hours= Unlock all Exs
4.What characters are unlockable? I want Roku But I don't think hes in this one..
I honestly dont know who Roku is, sorry.

But when you unlock a song, you unlock the song's character too. This doesnt apply to the extra characters you get after 7.5 hours.
5. I just got the game two days ago and the hardest level of song I can do is a 15...am I progressing ok?
Yeah, I started playing Pop'n in November and I can only do a 26 at best.
Also to note, Did you remember to turn off the "Wish on a star" unlock method?