This is likely the best reference I see on line
http://www.antiqueradio.org/recap.htm
You need to focus mainly on the large electrolytic filter capacitors in the power supply. They are the most prone to failure with age. Modern capacitors will be MUCH smaller. If you have a chassis mounted "twist lock" type can capacitor I generally replace this with discrete caps under the chassis, leaving the old can in place for aesthetics. There are articles on the web where people gut the can and slide the new caps into the shell.
Next up would be the paper/foil stage coupling and bypass capacitors, these are the cylindrical axial lead jobs. These can fail and modern film replacements are generally superior, but wholesale replacement of these may not be needed.
Replacement of the mica and ceramic capacitors in the RF tuned circuits is likely not necessary and doing so may mean more re-tuning is needed. I'd only replace these if I see a problem.
I would also go through the radio with an ohm meter and verify that the old resistors haven't gone too far astray as well.
The concerns of a hot chassis are valid, check before you find out the unpleasant way! An isolation transformer is wise when working on these radios when under power. As mentioned capacitors can hold charge too, although in an electronic circuit there are generally enough bleeding resistances that I don't worry much about it. After a few minutes everything will be safe. Old electrolytic caps have enough internal leakage to leak down on their own. High voltage motor caps and any power supply over 600v should indeed ALWAYS be discharged for safety though. I have a nice 4Kv 50uF film cap in a linear amp power supply, that one does deserve full attention! Working with one hand in a pocket if the circuit is hot is wise too.
Power up of an unknown vintage piece of electronics should be done in a controlled manner with a Variac (variable autotransformer) that allows you to bring the line voltage up slowly over a course of minutes/hours while watching for issues. To just flip the switch is rolling the dice for failures. If you don't have a Variac wire up an outlet with a 100w light bulb in series with the hot lead to the device. If something shorts the bulb will drop the full line voltage protecting the transformer and other parts. Current drawn is visually indicated by lamp brightness too
As for switches and controls buy a can of Caig Labs De-Oxit D5 spray. I first started using this magic-in-a-can in the mid 80's when I worked at a hifi repair shop. They have an excellent Fader lube too which I use on carbon track potentiometers to lubricate and preserve their life.
As for where to buy parts, I source most of my parts from Digi-Key in Northern MN. They are nice to deal with, sell individual parts to anyone and it was started by a Ham that I have met. (Trivia, the company name came from an early digital Morse code keyer kit that the founder sold) I have been quite happy with the Panasonic film and electrolytic capacitors. They are a great source for resistors and other bits too.
Other good suppliers are
www.tubesandmore.com
www.parts-express.com
www.mouser.com
www.thetubestore.com
