Yes, you can use them for both divinatory purposes and magical purposes! I use n-Getal all the time because of its healing powers and associations! I’m not sure about using them everyday for things but I don’t see why not!
There are some ogham fíd that aren’t recommended for magical purposes unless you use them very, very carefully such as h-Uath because of its association with terror, dread, and nightmares.
H-Úath can be used magically to turn negative forces against themselves, but should be used with extreme caution if at all. Cursing, while not advisable under most circumstances, is also a part of h-Úath’s magic and might be legitimately used for self-defense. It may be useful to call upon the energy of wolves and the sharp spikes of the hawthorn for protection and to drive away any malevolence that may be facing us, though great care must be taken so that the harm inherent in h_Úath doesn’t turn around and bite.
Weaving Word Wisdom by Erynn Rowan Laurie