We don't really give much to charity in terms of money. However my DH is the chair of the board of a local charitable trust and gives a lot of his (very precious) spare time to this. I also do voluntary work locally. We prefer the personal interactions through doing these things rather than giving money to faceless charities. It is easy to set up a SO or DD and feel smug about it. Much harder but more worthwhile to get stuck in at the coalface and actually do the work!
a) You can do both - give time and money. Many people who are not wealthy do this.
b) We don't feel 'smug' - that's generally a word used by those who don't give anything to charity to insult those who do.
c) Nothing 'faceless' about the two charities we give most of our time and money to.
One is the local hospice - we go in personally, we donate time to their events, we give them regular financial donations and lots of stuff to their charity shops.
The other is a very small charity working with a group of Maasai in Kenya, run by a family in Devon who travel out there regularly. We know the two individual children that we are sponsoring to go to school - they are the same ages/sexes as my children. They exchange drawings, photos and letters with my kids.
If you are very wealthy and don't give money to charity, you are in the wrong. Calling other people 'boasting' or 'smug' doesn't hide that as well as you think it does.