Which kind of adhesive is used and where do I buy it?
Which kind of adhesive in the Galaxy S5 screen?
Is there anything else I should worry to keep it as waterproof as possible?
The adhesive between screen and midframe is this one http://www.witrigs.com/oem-front-screen-.... But if you have disassemble the phone, you'd better be careful with the water even with this adhesive. The phone you DIY repair can't be same with the one came from professional machine.