Yes, but spread spectrum modulations are very much a minority among all our transmissions, so I see no reason to expect any different from other civilizations.
Today yes. But imagine that our technology gets refined in the following 10k years, even assuming no more technological breakthroughs, but only incremental improvements.
Even today we use some technology which is not really necessary to solve a given problem, just because it uses off the shelf components which are cheaper even if more complicated (e.g. a embedded cpu instead of dedicated and simpler electronics)
