Navigation electronics upgrade path

[rwoodnz]

Hi All

I am looking for help to find a low price, but still good, path through the nightmare of upgrading navigation. I a willing to use any of the major brands or combinations and only want to upgrade parts of the system where I need to or it provides very useful newer functions.

I'm also thinking it's better not to necessarily replace things but leave older systems there for safety duplication as well.

Current situation:
Dying Raymarine C70 plotter plus individual ST60 displays with depth, speed, wind speed and angle, and autopilot. There is GPS and VHF aerials. Analogue radar feeding to C70.

Wanting:
Modern radar (digital)
AIS
MFD at helm - a size bigger than C70.
Wifi connection for data to tablet - as much functionality replicated on the tablet as possible.

Please give me your thoughts on what combinations of equipment you see will achieve these goals, and whether I would need to do everything at once or if there are steps I can take as I can afford them.

Also researching:
FLS - can a 2D FLS replace a depth sounder in through hull hole and in providing the straight down depth data? Can its data show on an MFD or does it have its own screen?

Best wishes
Richard