author=supremewarrior
What do the icons represent?

From left to right:

Rum Bottle - HP (number next to it is lives or "number of bottles left")
Hourglass - Bullet time charge, smaller hourglass and purple number are how many bullet-time charges you have left to use. When you use a charge the large hourglass turns upside down and you get slow motion until it empties back to the default position (approx 3 seconds, I think).
Ink Bottles - Ink blast attacks. They clear the screen/ do damage to everything on the screen. You can hold 3 maximium hence the three little ink bottles.
Coins - Just coins, booty, treasure collected for spending.

At the very far right is the currently selected weapon's icon and ammo bar.

author=supremewarrior
Theres a shop to buy powerups then I'm assuming?

That's the plan at least, yeah :>