Can the roots from this plant/tree be invasive to drains or walls?
Yes, an Oleander does have considerations when planting near a home or structure.
Oleander is drought tolerant and sends it's roots deep along with more surface roots.
Plant a Oleander at least 12 to 18 feet from a sewer or water line.
Also consider the toxicity of a Oleander.
All parts of this plant are toxic, including roots. You will want to contact your local government to check for regulations in planting a Oleander.
Oleander should never be planted where children or pets are living.