Electronic – What’s causing bubbles in the transformer oil

When you say bread board, I'm assuming you mean solderless bread boards.

Soldering legs to individual SMD caps will be fairly difficult, and likely fragile. You should be able to buy through-hole caps that have sufficient voltage at RadioShack, or at just about any online electronics distributor (digikey, mouser, etc). Here is an example of a 50V through hole capacitor.

When I want to use SMD components on a breadboard, I usually attach them to a breakout board first, and then run wires or header pins from the breakout board. Bellin makes many different snap-out breakout boards like this. It's a little on the pricey side, though. You could make your own by cutting up some solder-type bread boards. SchmartBoard is another brand of adapters you could check out.

Before you design your smoothing capability, you need to specify what you want it to do.

'The current coming out should preferably be maintained around 180Amps.'

This is not a specification, and around is not a tolerance. It does sound like you want a constant current output, rather than a constant voltage. Or are you just using 'current' loosely? Would a constant voltage be OK?

At the risk of being obvious (this is to illustrate the need for a specification), you can approach zero voltage ripple on the output as you approach infinite capacitance. The two are precisely in inverse proportion. Less capacitance, more ripple. So, as capacitance costs money and takes up space, you can work out exactly how much capacitance you need, from how much ripple your application can tolerate.

The easiest way to produce a high ripple, high value capacitor, is to parallel several lower value caps. So yes, your idea of 90 off 2A capable caps to handle 180A is OK. You may not need as many as 90.

There are better ways to reduce the output ripple than simply racking up the capacitance, once the ripple becomes a critical specification.

The first is use of three phase power. The problem with single phase is the long period with no effective power coming from the mains, that has to be held over by the capacitors. Three phase reduces the ripple from raw rectified mains to a few percent, rather than the 100% of single phase.

The alternative is to use a SMPS, switched mode power supply. At this power, getting for 4kW, it should be power factor corrected. The design of a SMPS at this power level is non-trivial, and you would do best to buy something.