It's just the way it is said in Dutch "to look forward to" = "verheugen op", in combination with 'it/er' the 'er' and 'op' are combined to erop.
'to look forward to' = 'verheugen op'
'We look forward to' = 'Wij verheugen ons op'
'We look forward to it' = 'Wij verheugen ons er op', er and op are combined to erop making > 'Wij verheugen ons erop'
Hope that is clearer
No, because it is supposed to be 'wij hebben een zin in (something)'. If you use 'er', it comes after the verb. So it becomes 'wij hebben er zin in'.
Example: We vinden hardlopen leuk. We hebben er zin in.
definitely doesn't sound like that is a G. make sure you pay attention to all the previous questions and remember words they used.
I must say that a g like this in between two vowels is usually not pronounced as hard as in some other cases like ga or school.
Yes, it's anticipation. I believe it will be good when it happens and that I will like it. I feel good now just thinking about it.