Is neo4j able to replace mysql and preform equally well in terms of serving static data (fronted by redis)
Not sure what you're asking here, but I'll try to pick apart.
If you want to compare MySQL with neo4j, there is no true comparison because they're different products. Using one over the other is based on requirements, constraints, and SLA's, not because one is better than the other. If you need persistence, durability, and the utmost transactional integrity along with some nice database management tools, use MySQL. If you want to store interconnected social interests using an in-memory graph for quick retrieval and you're willing to sacrifice some reliability for performance, use neo4j.
...and perform equally well in terms of serving static data...
First of all, don't use a database to serve static data; for semi-complex objects (key/values, sets, hashes), use redis; for static content like images/css/js, use a reverse-proxy like nginx.
I was thinking about using MySQL with Neo4j initially. Some google searches pointed to less flexibility and more maintenance.
Forget those opinions; everyone's got one. Did those articles discuss requirements, constraints, and quality of service they were attempting to achieve but failed to do so, and why? I'm willing to bet their constraints were likely very different from yours. There is no such thing as a bad solution; only bad choices; that's why jobs in IT are plentiful because most of us are fixing someone else's idiotic decision.
Focus on exactly what you need, plan ahead, and make choices based on that, period.
So anyway, back to your question, if it were me, and based on the limited info you provided, I'd use MYSql and neo4j, simply because I like having reliability and persistence for important database operations (profile update, cc purchases, etc), while less-important changes like updates to social connections, interests, etc., still get persisted in the database but are also pushed asynchronously to the graph. If some updates fail or get stuck in limbo, no big deal, Suzie just won't get the latest play list or likes from her friends, but at least her credit card info is safe.
Of course, using both MySql and neo4j means more maintenance, but you can minimize that by loosening the coupling between MySQL and the graph. In other words, don't replicate your data model in neo4j, doing so would be a maintenance nightmare since any database change means changing the graph. In neo, store only referential identifiers and very basic, high level info (user_id, first/last name, album_id, album_name), just enough to generate master-level screens. If the user drills down into detail-level screens (clicks a user, album, etc), go to the database, or redis, and get the full details for those objects. That's a good balance when using both products, a bit more work, but certainly manageable if done right.
Here's some extra info for you, hope it helps...
Is it a good idea to use MySQL and Neo4j together?
