Assuming this is on a beta multiplayer server, the spawn area or other structures and areas around them may be protected or you may be suffering from severe lag. In beta you have to use the appropriate tool to damage blocks properly and you have to hold the mouse button down until the block is destroyed.
e.g.
Pickaxe used for stone and obtaining ores, punching is really slow on stone
Axe is used for wood still easy if you punch it
spade is used for dirt and sand still easy if you punch it
(you can 'mine' without tools but it takes longer)
As the mouse button is held down it appears that the block sustains damage, hold down until the block is destroyed
you probably hit f1, that makes your hotbar disappear
There could be something wrong with the mod, because that shouldn't happen. Items that you throw should only disappear if they hit cactus or lava, or if they are laying there for a while. You could try reinstalling the mod.
You hit the F1 key to made your hot bar disapear.
In order to get pumpins in Minecraft you just punch them or you can hit them with ANYTHING
Just hit f6 or f8, forgot which one but just try the f keys and eventually something will work.
hit a two times
hit t then type it in
Hit F5
die, then hit "respawn"
Hit F10 again...if it doesn't get fixed, hit F8.
Hit it (left click it).
Hit the T key.