My stupid re-silicone questions!

[Coasting]

So i'm trying to re-seal a tank right now, I think I'm doing it properly (Yeah right... this is hard)! Do I have to remove the silicone along the bottom inside of the tank even if it still looks good? What about when I get to the top where the black plastic rim is? There are chunks up in the corners I'm finding hard to reach, are those necessary to totally remove if the water wont be going that high?

Anyone in the area want to come help? LOL.. I can provide drinks....

BTW home hardware has the aquarium safe silicone on sale $2.46 each!
http://www.homehardware.ca/en/rec/in...5?Ntt=silicone