The Vidiot is just a rather simple resistor array. The swollen 'bumps' are quite normal - SMD resistors covered with some protective paint.
Actually there's nothing in there that can break easily, I've never seen a damaged one.
The Hires Denise is not causing split memory. If you just replace the 512K Agnus on an old board with a 1 MB one, you need to adjust one of the jumpers to remap the 512 MB slow fastmem ('Ranger') to gain 1 MB chipram.
