This answer is assuming you are on any 0.9.x version (lower versions would already have been booted off in the previous hardfork) currently. Note that 0.10 is going to be released soon. In general it is advised to use the latest binaries, because they contain bugfixes and new features.
What will happen (if anything) to my actual wallet during this hardfork update?
Nothing basically. The only (minor) change is that it will enforce coinbase transactions to be split in denominations. See line 123 of the dev logs.
Will it change address?
No. Addresses will never change during a fork.
Do I need to do something to preserve/transfer my balance?
No coins have to be moved. Thus, to answer you question, no you don't have to do anything.