New climbing shoes and cracking inner side rubber.

Hello,

I am pretty new to climbing and I bought a pair of climbing shoes. I went to the store and spent one hour trying them and even though i wear a 42 1/2 (a 9 1/2 american), we decided with the very patient lady for a size 41 (size 8 american).

I've been told that these kind of shoes fit way tighter than normal shoes, so I've been wearing them at home too, trying to get them to stretch (they are just a bit too painful to wear for extended periods of time at the gym, let's say the first 20 minutes are ok, then my right foot dies and it's done).

I noticed today that cracks appeared on the inner side rubber as you can see in this pic

http://imgur.com/Kt2gwGD

Both shoes are affected in the same way. Is it normal? Or should I bring them back to the store? The shoes are a popular model around here, wildclimb bat.

Also, I have a hard time deciding how much pain is enough with these kind of shoes. Even in the wiki, one article says "pain is insane!" and the other says to get shoes a size smaller. Kinda contrasting info! It seems that the common opinion is pain IS the way to go...

Thank you!