The first one is a through hole connector, of course the pins are going to extend below the pad... It's also less than 2.5mm, how tight is the clearance on the underside of your board?
The second is a surface mount connector and is meant to be installed with solder paste applied and in a reflow oven, the method you've described with a via through the board can work for heat transfer, so you'd apply solder paste/flux to the pad on the top, solder the edge pins in place, then heat the paste in the middle from the back. Could be a bit tricky to inspect, depending on clearance and how easy it is to see. If you make the via large enough for solder to flow through, you may be able to see from the underside, but I'd still use the solder paste on the top side to be sure, even if hand soldering.
Right angle signal trace is not going to matter at 10kHz (I assume you meant 10MHz), or 10MHz, or likely even 100MHz. In fact, 18GHz SMA connectors are REALLY overkill for applications under 1GHz, I'd look into using some other kind of test point, pad, or connector.