Can crack sealing precede a seal coat or hot mix overlay? My concern is that the crack seal material could have a negative reaction with the new surface material.

Crack Sealing prior to rehabilitation is a good idea. The majority of complaints concerning crack sealer problems arise when an excess of material is left on the surface of the pavement either due to overfilling or expansion of the sealant. The best method to treat cracks is to route a vessel 5/8″ x 5/8″ or 3/4″ x 3/4″ and use a modified joint sealer that meets ASTM 3405 or ASTM 3405-modified specifications, and be careful not to overfill the joint. The top of the sealant should be left about 3 to 6 mm (1/8″ to 1/4″) below the top of the crack. For more details on proper crack sealing procedures and all maintenance methods, please refer to MS-16, Asphalt in Pavement Maintenance.