Numidian Campaign: those pesky Egyptians!!

[ReluctantSamurai]

cannot build more than ports, although I can use shipwrights/ dockyards when build before I arrived

You should check your "export_descr_buildings" directory. In the "building port_buildings" section under shipwrights/dockyards, there is a list of factions that can build them. IIRC, Numidia's capabilities in this respect, are lumped in with Carthage. Every faction has the capability for Shipwrights, no exceptions. Only Carthage, Eastern, Parthia, Greek, and Roman, are listed for Dockyards. I've played a Numidian campaign several times, and I can tell you I could construct dockyards and recruit quinqueremes

there is no law and order temple

The Temple of Baal is as good as it gets for the Numidians...20%/20% Law/Happiness. Not as good as some Roman or Greek temples, but better than a lot of barbarian cultures

Where is your capital? A screenshot of the extent of your current empire would be helpful in determining the best place to put it

You do need the archers close to the banks of the river and close to the bridge to fire accross

I would highly recommend that you keep your archers away from the river bank. Since Shogun I, the best arrangement for bridge defense is a wide semi-circle where the infantry is far enough from the river to not incur arrow fire from the opposite bank. Position your archers on the outside edges of the semi-circle facing inwards towards the bridge (and behind the infantry). If you are facing multiple stacks, try and keep at least two archer units in reserve for when the initial defenders run out of arrows. Remove the fire-at-will, and have them tactically grouped into two units. The reason for this is that when troops exit the bridge on your side, they typically turn right or left trying to flank you (which they can't). Arrow fire from the rear (or side) is twice as decimating as frontal fire...so activate the group that hits them in the rear when they turn.

Keep your cavalry to the outside & rear of the semi-circle to "escort" routers off of the battlefield

Using this method, on occasion, I've managed to kill every single attacking soldier, even with multiple attacking stacks.

All that practice in Shoggie I served me well in RTW

Also, (sorry, RS), don't scorn to use slingers against light infantry, and they also will help against chariots.

No need to apologize Just a matter of preference...