Is it possible to convert infrared energy into electricity?

Silicon solar cells can convert the shorter wavelengths of IR to electricity: https://www.solarquotes.com.au/blog/uv-solar-panels/

You can also concentrate solar IR and use the heat to generate steam to spin turbines for electricity: https://i1.wp.com/innovationtoronto.com/wp-content/uploads/2015/12/Solar-Thermal-Power-Plant_forcetoknow.com_.jpg?resize=627%2C221

Yes. All light can be used for solar power.

Yes, any kind of energy can be converted into any other kind.

If you can collect/focus enough infrared to make high temperatures, you could use a variety of current tech to make the electricity, like @RocketGuy ‘s second example steam turbines.
the infrared can heat some thermocouples as in some deep space probes (heat source, compact radiodecay reactor).