Since I also have this laptop some pointers: (May not totally apply to your case since mine came with Windows 8 and installed drivers, if you are reinstalling from scratch you might have a different experience.)
Download the drivers from http://us.acer.com/ac/en/US/content/drivers (just enter "Aspire V5-573G") and install them
I think I compared the versions to the already installed versions and skipped identical drivers.
Geforce Experience was installed, it can download the latest nVidia drivers and install them so I'd disagree with the statement "on laptops with switchable graphics you generally can only get them from the manufacturer itself" since the reference drivers seem to work fine. After all, Optimus (that's what nVidia's switchable graphics is called) was created by nVidia so it makes sense that it works with their drivers.
I also manually installed newer Intel graphics drivers (look for "Intel HD Graphics 4400").
You should definitely read up on Optimus. It is not always autodetected, the driver includes a list which applications/games should use the integrated or the discrete GPU. You can edit this list, eg. make new entries, and you can also tell it to use integrated or discrete graphics for everything which doesn't have an own entry or where the entry says that the global setting should be used.
There is also a global autodetect setting but I didn't try how that works exactly.
If possible I would try to use integrated video as long as possible as the machine can get quite loud when using the nVidia chip.
As for "OpenGL games tend to turn into a lagfest if graphics aren't manually switched" - I think that depends, for older OpenGL games like Doom 3 the integrated graphics might be OK depending on the resolution.
Re "If you want to run old games, it's better to set only discrete gpu because there are some incompatibility with old 3D Engine": My experience was the opposite, some old games (Frogware Sherlock Holmes series) refused to run with nVidia graphics but ran fine with Intel graphics. Unfortunately I couldn't find an option to disable Optimus altogether (in that case the Intel driver won't be loaded at all), I have seen this in a different laptop.