Jose--
Your new car appears to be in fantastic cosmetic condition, and that's the most important thing.
Problems with the air suspension are almost always related to the control valves--2 in front, one in rear plus the mainvalve that is located next to the left inner fender. The air bags themselves are usually OK even if they have some minor surface cracks. MUCH has been written on this and the M100 site with respect to the 300SEL 6.3, which uses the same system. You will need to work with a reputable specialist to get your suspension straightened out, but once you do it will provide a truly remarkable ride.
As for your engine, the ticking could be a misadjusted valve lifter...they are mechanical on the 3.5 engine or that era. But you'le also want to have one who really knows these older cars thoroughly check it out. Pierre Hadary in FL is one of the best ...and does house calls! Might be wise to have him do a thorough evaluation. Its such a pretty car, it will be worth it.

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Berfinroy in CT
Present vehicles:
1973 300 SEL 4.5
1959 Rolls Royce Silver Cloud I
1973 Citroen DS23 EI five speed
Past vehicles;
1959 Thunderbird convertible/430
1958 Bentley S 1
1976 ex-Max Hoffman 6.9
1970 300SEL 2.8
1958 Jaguar MK IX
1961 Jaguar MK IX
1963 Jaguar E-type factory special roadster
1948 Plymouth woody
1955 Morgan plus 4
1966 Shelby GT350H Mustang