30 psi is on the high side. If you have an "auto-filler" valve, that's what usually sets the system pressure- it's adjustable, but they can leak at the valve seat (a bit o' grit or pitting will do it), which would slowly raise the system pressure to whatever your incoming water pressure is. The solution is to close the isolating valve (usually a ball-valve or gate valve between the auto-fill and your potable water distribution plumbing) and drain the system until it hits the pressure you want. Most homes are good to go at 12psi, low mass boilers like yours are often happier at 15 psi. If the system has an indirect-fired hot water heater on it, a leak in the heat exchanger could have the same pressurizing consequences to the system.
The boiler is probably rated for 50psi, but if the expansion tank was pre-charged to 12-15psi running the system at 30psi isn't so great- the expansion tank will be beyond where it has much room for system water expansion as the temperature of the system rises.
Replacing the expansion tank is not a remedy for a system that's running at high pressure. If that's why the contractor swapped it out, (could it have been for other reasons?) their competence is pretty questionable.
It's normal to have steady condensation when the system temp isn't running anywhere near it's max output. Letting it drip onto concrete isn't such a good thing. The little condensate pumps used for managing air conditoining condensation work fine for re-directing condensing boiler condensate to a drain (as would be required by code in most states.) Natural gas condensate is only mildly acidic, similar to the acidity of red wine, but chronic dumping onto concrete will compromise the concrete. (You could open up a sump a that point and dump it into the soil without damaging your slab, but that's not a code-approved installation either.) The amount of condensation you get depends on the operating temp of the system, in particular the temp of the water returning to the boiler from radiation. The cooler it is, the higher the efficiency, and the more condensate drip you get. When setting up the system it's worth adjusting the temperature down to the minimum that actually keeps up with the heat load. (Look up in the manual how to program the "outdoor reset" curve.)
The Solo 110 is on the extra-big side for 80-90% of the houses in the US, but it probably the most-commonly installed size in that lineup, even though the -60 would usually be a better choice for both efficiency and steady-temp comfort. But as long as it isn't short-cycling on zone calls during mild-weather days you'll still get decent efficiency out of it.