Day Trip to Kobe July

Is it better to travel weekday or weekend .
We would like to go from Namba to NunobikiHerb Gardens & the have lunch in Chinatown (how do we travel easily ? before returning back to Namba
Should we consider Shinkansen ?
If so how much would it cost (4 teenagers not on rail pass)

Namaba to Osaka Station
Osaka Station to Sannomiya Station
Walk or take bus to Ropeway
Ask tourist office at station what bus to take

If have rail pass take train from Shin-Osaka to Shin-Kobe Station
Since Shin-Kobe and the mountains are both north of the city it makes things easier. East Exit has a tourist office? Ask what bus to take. It is a 2 minutes run. Bus has words herb garden in English as in drives along.

Thank You 2 Last questions
Approximately,how much would it cost for the Shinkasen Shin-osaka-Shin-Kobe one way ?
1 Adult+ 3 Teenagers ,student cards -none on Rail pass
And then could we take the standard train Kobe Station to Nanba
(Again ay ideas on cost)

I do not recommend that you go to Kobe by Shinkansen. If you go to Shin-Kobe by way of the Shin-Osaka from Namba, in the case of using a non-reserved seat, one-way fare is 1,780 yen. Passengers teenager is also charged as an adult.
http://www.hyperdia.com/en/cgi/en/search.html?dep_node=NAMBA(SUBWAY)&a...

I recommend that you purchase the Kobe Machimeguri Oneday Coupon for your trip. Price of it is 1,580 yen. You can be purchased at Higashi limited express ticket counter, located in Osaka Namba Station of Hanshin line. The round-trip fare to Sannomiya is included, it will be available Kobe subway, Kobekosoku Line, and Port Liner.
http://www.surutto.com/tickets/ticket_koube_1day.php#large_area

The coupon of 700 yen for the payment of tourist facilities are attached to it. You will be available as part of the admission fee of herb garden it.

Thank You for your good advice.
It is greatly appreciated