[1]. The sides of my cake are crunchy or burnt. 

One problem, lots of possible reasons: a/ too much fat has been used to grease the tin, b/ the cake tin's not sufficiently lined c/ the oven's too hot, d/ the cake's been left in the oven for too long or e/ it contains a fat not suitable for baking.

[2]. I can't get my cake out of the tin. 

Make sure your baking tin is well lined. You can't go wrong with baking parchment on the base and around the sides of your tin. Use a smear of butter on the inside of the tin to stick the parchment in place.

[3]. My cake is very dense. 

This could be because a/ the cake mixture hasn't had enough air beaten into it, b/ the eggs were added too quickly and curdled or c/ there's not enough raising agent.

[4].  My cake has spilled over the sides of the tin. 

The cake tin is too small. It's always best to use the tin size stated in the recipe. If you don't, avoid filling the tin more than three-quarters full and adjust cooking times accordingly.

[5].  My cake is burnt on top but still isn't cooked in the centre. 

This happens when the cake tin is too small. 

Dense cake that is under done in the middle, but "crispy " at edges is due to an ingredient mistake.  Measure carefully.  Also, make sure everything, including eggs, are room temp when mixing.  The crispy edges are due to being in the over too long to try to get that center done....been there...