1) I personally have never tried to create a dimstyle via LISP methods, but I suppose the way I would go about it is to set all the dim variables to how I would like the dim-style to be:, i.e.
DIMADEC 0 Angular decimal placesDIMALT Off Alternate units selectedDIMALTD 4 Alternate unit decimal placesDIMALTF 0.0394 Alternate unit scale factorDIMALTRND 0.0000 Alternate units rounding valueDIMALTTD 4 Alternate tolerance decimal placesDIMALTTZ 0 Alternate tolerance zero suppressionDIMALTU 8 Alternate unitsDIMALTZ 0 Alternate unit zero suppressionDIMAPOST Prefix and suffix for alternate textDIMASZ 3.0000 Arrow sizeDIMATFIT 3 Arrow and text fitDIMAUNIT 0 Angular unit formatDIMAZIN 0 Angular zero supressionDIMBLK ClosedFilled Arrow block nameDIMBLK1 ClosedFilled First arrow block nameDIMBLK2 ClosedFilled Second arrow block nameDIMCEN 0.0000 Center mark sizeDIMCLRD 5 (blue) Dimension line and leader colorDIMCLRE 5 (blue) Extension line colorDIMCLRT 2 (yellow) Dimension text colorDIMDEC 2 Decimal placesDIMDLE 0.0000 Dimension line extensionDIMDLI 2.0000 Dimension line spacingDIMDSEP . Decimal separatorDIMEXE 2.0000 Extension above dimension lineDIMEXO 2.0000 Extension line origin offsetDIMFRAC 0 Fraction formatDIMGAP 2.0000 Gap from dimension line to textDIMJUST 0 Justification of text on dimension lineDIMLDRBLK ClosedFilled Leader block nameDIMLFAC 1.0000 Linear unit scale factorDIMLIM Off Generate dimension limitsDIMLUNIT 2 Linear unit formatDIMLWD -2 Dimension line and leader lineweightDIMLWE -2 Extension line lineweightDIMPOST Prefix and suffix for dimension textDIMRND 0.0000 Rounding valueDIMSAH Off Separate arrow blocksDIMSCALE 0.0000 Overall scale factorDIMSD1 Off Suppress the first dimension lineDIMSD2 Off Suppress the second dimension lineDIMSE1 Off Suppress the first extension lineDIMSE2 Off Suppress the second extension lineDIMSOXD Off Suppress outside dimension linesDIMTAD 3 Place text above the dimension lineDIMTDEC 2 Tolerance decimal placesDIMTFAC 1.0000 Tolerance text height scaling factorDIMTIH Off Text inside extensions is horizontalDIMTIX Off Place text inside extensionsDIMTM 0.0000 Minus toleranceDIMTMOVE 2 Text movementDIMTOFL Off Force line inside extension linesDIMTOH Off Text outside horizontalDIMTOL Off Tolerance dimensioningDIMTOLJ 1 Tolerance vertical justificationDIMTP 0.0000 Plus toleranceDIMTSZ 0.0000 Tick sizeDIMTVP 0.0000 Text vertical positionDIMTXSTY STANDARD Text styleDIMTXT 2.5000 Text heightDIMTZIN 0 Tolerance zero suppressionDIMUPT Off User positioned textDIMZIN 8 Zero suppression