"The difference between SMF and MMF is that with SMF, the light follows a single path through the fibre, while MMF uses multiple paths."
This bit is wrong/misleading. The diference is modes supported, not paths. OMx then defines the modal bandwidth of the multimode fibre which affects the distance, and also future proofing an installation. So OM1 & OM2 don't support 40Gbps or 100Gbps.
"Both SMF and MMF come in two wavelengths, 850nm and 1300nm, with the latter supporting longer distances."
SMF supports many more wavelengths, hence why it's used for DWDM. 850nm isn't generally used AFAIK, but that's more to do with SM v MM. Pretty much all common SFP's @850nm are intended for MM fibre. If you connect those to SM fibre there's a mismatch between expected core size and although it may work, it's generally a bad idea.
"The most widely used connector is the SFP+"
An SFP is a transciever, not a connector. Connectors would be FC, LC, SC, E2000. Important because they're the bits on the end of the fibres and connectors on SFPs or other kit. LC and E2000 probably most useful on an ODF/patch panel given connector size & density, and for E2000, built in dust caps. Patch cables can have different connectors each end.
"If you need to get 10GbE in longer distances, but not quite in the miles range, using MMF cables such as OM3 or OM4 with SFP+ connectors would be a good option."
I'd suggest that's a bad option. Key thing is to come up with a plan and stick to it. So OM4 offers the best speed/distance combo for local connections. If that's within a smallish datacentre, stick with that so you can do 100G if/when you need it over a typical room-sized distance. Get color coded patch cables made up, stick samples on a board somewhere prominent and set your BOFH on anyone who doesn't follow it. This will make future maintenance easier.
For longer distances, ie inter-room, inter-floor or inter-building, use SM fibre. Or make sure you run plenty of spare fibres. OM4 will support 1x100Gbps. If you need more, or want to segment then the ability to add a WDM or DWDM mux gives you more flexibility in the future, and most of that kit is designed to work over SMF.