Micro soldering

I'm embarking on a harebrained project to try adding a decent RF connector to a smartphone that doesn't have one. It's a Samsung Galaxy S3.

It has a test RF connector on the circuit board which is accessible if you remove the battery cover. It's not a socket though, it's a purpose designed test point which expects a precisely machined probe to be applied to it during factory testing. There exists no connector designed to clip on and stay permanently attached. The test connector incorporates a through-connecting switch corresponding to coax inner conductor, it makes / breaks the line coming from the phone's internal antenna as it heads toward the phone's main board.

I don't know whether, the connected probe ends up connecting to the internal antenna or the main board.

Not that it matters. What I want to do is desolder this test connector, and then replace it with something fairly stonky like an SMA connector, wired direct to the phone's radio rather than it's antenna. So that I can play around properly with collinears and yagis etc.

To do this I will have to desolder & solder some pretty tiny stuff probably closely surrounded by all manner of SMT semiconductors. I'm really good with a soldering iron on big fat 70's circuitboards and veroboard. But no experience at all with tiny stuff. Plus, I have the eyes of a mole these days.

Please give me your tips for soldering ultra tiny stuff.

I have a dremel-type tool with lots of attachments, that's about the only tool I have that I think might be relevant. What sort of iron should I get for this type of work?

Are those helping hands type jigs a must-have?