Various Replay Gain tags

I think I know the answer(s), but thought I should canvas opinion too.....
In total I have 32000 flac tracks, some of which have one or more tags populated relating to volume and replay gain. I've listed below the volumes of tracks with each respective tag populated. My questions are:

  1. is it good practice (necessary even) to use the volume/replay gain tags? (I do want all songs to be the same volume when playing back).
  2. if answer to 1) is 'yes', should I remove the existing tags and then analyse my complete library? The advantage of this approach is consistency as I have never set the tags myself and at least afterwards all volume tags will have been set in the same way.
    Many thanks in advance.
    Tags and no.s of tracks:

PEAK LEVEL (R128) 980
replaygain_album_gain 5901
replaygain_album_peak 5889

I use ReplayGain (RG) tags for my complete library of about 114,000 tracks. I mostly used dbpoweramp for ripping (and added my TRACK and ALBUM gain values when ripping). But one can easily add RG tags after the fact (they are just tag info, and don't modify actual audio of the file). dbpoweramp can use a utility DSP in its conversion program to add RG tags, by album, automatically. But it is not free. foobar2000 does a great job on adding RG tags. Install foobar2000 and it has a ReplayGain scanner built in. Then you can literally load up your enitre library, and with a few clicks, have it redo/add RG ALBUM and TRACK tags. You can tell foobar2000 in its settings to analyze your files by ALBUM tags or by FOLDER, etc.

All the servers/players I use can be set to automatically use my RG tags. And in fact, they have options that are smart enough to use TRACK RG values when playing a playlist of tracks from different albums, but ALBUM RG values when playing tracks from the same album. This allows the intra-album dynamics to be maintained when playing an entire album.

Both foobar2000 and dbpa are using the modern R128 approach to adding RG tags. And default for both regarding reference loudness is LUFS = -18.